Excess Methyllithium Research Articles

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet-Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids.

We present a systematic investigation on an improved variant of the N-acyl-Pictet–Spengler condensation for the synthesis of 1-benzyltetrahydroisoquinolines, based on our recently published synthesis of N-methylcoclaurine, exemplified by the total syntheses of 10 alkaloids in racemic form. Major advantages are a) using ω-methoxystyrenes as convenient alternatives to arylacetaldehydes, and b) using the ethoxycarbonyl residue for both activating the arylethylamine precursors for the cyclization reaction, and, as a significant extension, also as protective group for phenolic residues. After ring closure, the ethoxycarbonyl-protected phenols are deprotected simultaneously with the further processing of the carbamate group, either following route A (lithium alanate reduction) to give N-methylated phenolic products, or following route B (treatment with excess methyllithium) to give the corresponding alkaloids with free N–H function. This dual use of the ethoxycarbonyl group shortens the synthetic routes to hydroxylated 1-benzyltetrahydroisoquinolines significantly. Not surprisingly, these ten alkaloids did not show noteworthy effects on TPC2 cation channels and the tumor cell line VCR-R CEM, and did not exhibit P-glycoprotein blocking activity. But due to their free phenolic groups they can serve as valuable intermediates for novel derivatives addressing all of these targets, based on previous evidence for structure–activity relationships in this chemotype.

Synthesis of [3]ferrocenophane-bridged Cp–amido zirconium complexes and ansa-zirconocene complexes and their use in catalytic polymerisation reactions

Starting from 1,1'-diacetylferrocene the ortho-amino,α-dimethylamino[3]ferrocenophane system 3 was prepared. This was converted to the o-imino,α-Cp-derivative 6. Subsequent treatment with e.g. an excess of methyllithium followed by ZrCl(2)(NMe(2))(2)(thf)(2) and Me(2)SiCl(2) eventually gave the [3]ferrocenophane based Cp-amido zirconium complex 11b. In a similar way the [3]ferrocenophane derived fluorenyl-Cp ansa-zirconocene dichloride complex 20 was obtained. The 20-methylalumoxane (MAO) system is an active homogeneous Ziegler-Natta catalyst for ethylene polymerization. The 11b-MAO system reacts efficiently with an ethene-1-octene mixture to yield a mixture of linear polyethylene plus the ethene-1-octene copolymer. The compounds 5, 8, 10b, 11b, 13, 14, and 20 were characterized by X-ray diffraction.

Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion.

Theoretical and synthetic studies of the tricyclic 10pi-electron hydrocarbon cyclobuta[1,2:3,4]dicyclopentene (1), a nominally aromatic structure that has never been synthesized, are described. Geometry optimization by density-functional-theory calculations (B3LYP/6-31G(d,p)) predict that 1 is a D(2h) symmetric structure with nonalternant C-C single and double bonds. The calculations also predict that 1 is 4.7 kcal/mol higher in energy than the isomeric hydrocarbon 1,6-didehydro[10]annulene (2), a molecule known to isomerize to 1,5-didehydronaphthalene (4) above -50 degrees C. Calculated enthalpic changes of homodesmotic reactions support the notion that 1 is an aromatic molecule with a resonance stabilization energy (RSE) about half to two-thirds that of benzene on a per-molecule basis. Investigations of potential synthetic pathways to 1 initially utilized as starting material the tricyclic carbonate 11, the product of an intramolecular [2 + 2]-photocyclization reaction. In these studies, 11 was transformed in several steps to the distannane 12, which upon treatment with boron fluoride ethyl etherate is believed to have formed the unstable hydrocarbon bicyclopentadienylidene (13). In an effort to avoid cleavage of the central, four-membered ring of unsaturated tricyclo[5.3.0.0(2,6)]decane intermediates (perhaps the result of 10-electron electrocyclic ring opening of the tetraene 8), synthetic approaches to 1 employing cobalt-cyclobutadiene complexes 18 and 19 were pursued. Treatment of 18 with excess methyllithium led to the novel cobaltacyclic product 30, and dehydration of 19 in the presence of pyridine produced the ring-opening cobaltacyclic product 35. It is proposed that both processes may occur by a 10-electron electrocyclic ring-opening reaction of eta(2)-organocobalt intermediates. These processes may be related to the hypothetical transformation of tetraene 8 to bicyclopentadienylidene (13).

Reactions of Highly Branched Fluoroolefins with Methyllithium and Methylmagnesium Bromide: Formations of Unexpected Polyfluorocyclobutene and Polyfluoropentadiene Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reactions of highly branched fluoroolefins with methyllithium and methylmagnesium bromide: formations of unexpected polyfluorocyclobutene and polyfluoropentadiene compounds

Introduction of a methyl group into hexafluoropropene trimers was achieved by reactions with organometallic carbon nucleophiles. Unusual cyclization and defluorination occurred simultaneously with a formation of methylated polyfluoroolefins: excess methyllithium provided a polyfluorocyclobutene compound, while a polyfluoropentadiene derivative was formed by use of excess methyllithium.

Coordination and organometallic complexes of iron containing o-phenylenebis(dimethylphosphine) (pdmp). Crystal and molecular structure of [Fe(η2-C2H4)(pdmp)2

Routes to hydrido- and organo-iron complexes of the bidentate ligand o-phenylenebis(dimethylphosphine), o-C6H4(PMe2)2 (pdmp), have been developed, starting from trans-[FeCl2(pdmp)2]. Reduction of trans-[FeCl2(pdmp)2] with LiAlH4 gives the dihydride, cis-[FeH2(pdmp)2], there being no evidence for an intermediate monohydride [FeHCl(pdmp)2]. Treatment of trans-[FeCl2(pdmp)2] with an excess of methyllithium gives [FeMe2(pdmp)2], isolated as a cis/trans-mixture, the methyl groups of which are cleaved by an excess of HX to give [FeX2(pdmp)2] (X = Cl, Br), predominantly in the form of the cis-isomers. Other new complexes include [FeCl(Me)(pdmp)2] (cis/trans-mixture) and [Fe(L)(pdmp)2] [L = CO, η2-C2H4, η2-C8H8, η2-1,4-C8H6(SiMe3)2, η2-C4H6, η2-PhC2Ph and η2-MeC2Me]. Treatment of trans-[FeCl2(pdmp)2] with sodium–naphthalene generates the hydrido(naphthyl)iron(II) complex [FeH(η1-C10H7)(pdmp)2] as a cis/trans-mixture in tautomeric equilibrium with a zerovalent iron naphthalene complex [Fe(η2-C10H8)(pdmp)2]. Single crystal X-ray analysis shows that [Fe(η2-C2H4)(pdmp)2] has a distorted octahedral structure in which the ethylene is twisted by ca. 15° relative to the FeP4 skeleton, probably because of steric effects. In solution the coordinated ethylene rotates about the coordination axis with a free energy of activation ΔG‡ at 324 K of 67 kJ mol−1, as estimated from variable temperature 1H and 31P NMR spectra. In the cyclooctatetraene complexes [Fe(η2-C8H8)(pdmp)2] and [Fe{(η2-1,4-C8H6)(SiMe3)2}(pdmp)2] there is also a lower energy process in which the Fe(pdmp)2 unit migrates between the double bonds of the eight-membered ring. The strong electron-donating ability of the Fe(pdmp)2 fragment is indicated by the low value of ν(CO) in [Fe(CO)(pdmp)2], the highly shielded 1H and 13C nuclei of coordinated ethylene in [Fe(η2-C2H4)(pdmp)2], the Fe–C and CC bond lengths in the Fe–C2H4 unit [2.052(8) and 1.418(10) Å, respectively], and the facile reversible protonation of the coordinated ethylene by methanol or ethanol. Treatment of [Fe(η2-C2H4)(pdmp)2] with HBF4·OEt2 gives initially a complex cis-[Fe(BF4)(Et)(pdmp)2], in which the ethyl group may be agostic, and finally cis-[Fe(BF4)2(pdmp)2]. The coordinated BF4 groups of the latter compound are displaced by acetonitrile to give cis-[Fe(NCMe)2(pdmp)2](BF4)2. The BPh4 salts of the cations [FeBr(NCMe)(pdmp)2]+ and [Fe(NCMe)2(pdmp)2]2+ have also been isolated as mixtures of cis/trans-isomers from cis-[FeX2(pdmp)2] (X = Cl, Br) and acetonitrile.

High yield synthesis of [ 11C]-acetone through selective quenching of methyl lithium

Carbon-11 labeled acetone is a useful radiosynthetic precursor. Previously, strict control of no-carrier-added stoichiometry was required to prepare it from reaction of CO 2 and methyl lithium. However, excess methyl lithium may be selectively quenched to avoid reaction with nascent acetone to give tert-butanol. We report a simple pKa-based strategy to sequentially and selectively quench MeLi and acetone to give yields of up to 100% acetone even in the presence of a large excess of MeLi. The method gives good yields of acetone under conditions that previously precluded its synthesis.

A New Synthesis of Occidol

Sodium borohydride reduction of 5,8-dimethyl-3,4-dihydronaphthalen-1-(2H)-one (4) yielded 5,8-dimethyl-1,2,3,4-tetrahydro-1-naphthol (5). The tetralol 5 on Vilsmeier-Haack reaction with N,N-dimethylacetamide yielded 1-(5,8-dimethyl-3,4-dihydro-2-naphthyl)ethan-1-one (7) which on hydrogenation over Pd/C afforded 1-(5,8-dimethyl-1,2,3,4-tetrahydro-2-naphthyl)ethan-1-one (8). The tetralol 5 on Vilsmeier-Haack formylation gave 5,8-dimethyl-3,4-dihydro-2-naphthaldehyde (9) which on reduction with lithium aluminium hydride followed by oxidation with the Jones reagent furnished 5,8-dimethyl-1,2,3,4-tetrahydro-2-naphthoic acid (11). The acid 11 on treatment with excess of methyllithium yielded (±)-occidol (1); with two moles of methyllithium it yielded ketone 8, which on reaction with methyllithium furnished (±)-occidol (1).

Synthesis of 1,1,5,6-Tetramethyl- and 7-Isopropyl-1,1-dimethyl-1,2,3,4-tetrahydronaphthalene

4-(2,3-Dimethylphenyl)butanoic acid (4) was treated with excess of methyllithium to yield 5-(2,3-dimethylphenyl)-2-methylpentan-2-ol (6) which was cyclodehydrated using Dowex 50W-X8 resin, trifluoroacetic acid or polyphosphoric acid (PPA) to furnish 1,1,5,6-tetramethyl-1,2,3,4-tetrahydronaphthalene (1). The acid 4 was cyclized with PPA to furnish 5,6-dimethyl-3,4-dihydronaphthalen-1(2H)-one (5) which was converted into 1 by reaction with dimethylzinc and titanium tetrachloride. 4-(4-Isopropylphenyl)butanoic acid (7) on esterification followed by Grignard reaction with methylmagnesium iodide furnished 5-(4-isopropylphenyl)-2-methylpentan-2-ol (9), which was cyclodehydrated as above to yield 7-isopropyl-1,1-dimethyl-1,2,3,4-tetrahydronaphthalene (2).

Generation of the 1,3-Phosphasilolene Skeleton from Ortho-Silylated Biarylphosphonates

Treatment of diethyl 2-(3-trimethylsilyl)biphenylphosphonate 15 with excess methyllithium affords a mixture of the 2H-benzo[d]-1,3-phosphasilolen-1-one 16 together with the silyl transfer product 17. Deuterium incorporation studies show that the mechanism involves the conversion from 15 to 19 and 20, followed by formation of a siliconate intermediate 21. Cleavage of an exocyclic Si−C bond affords 16 while endocyclic C−Si cleavage leads to 17. The phosphasilolene structure 16 is confirmed by X-ray crystallography.

Preparation and some properties of Mn(I) metallocenylacetylide and the related complexes

The reaction of lithium ferrocenyl- or ruthenocenylacetylide and MnBr(CO) 5 at low temperature gave the corresponding Mn(I) metallocenylacetylide complex in a moderate yield. In the presence of excess methyllithium, (tetracarbonyl)(1-ferrocenyl-buten-3-one-1-η 1, O) manganese and 4,6-diferrocenyll-α-pyrone were isolated, in addition to the Mn(I) ferrocenylacetylide complex. The former was also obtained in the reaction of MnMe(CO) 5 with FcCCH. The structures these two complexes were determined by a single crystal X-ray analysis.

Synthesis of Transient Silenes by a Modified Peterson Reaction

AbstractTris(trimethylsilyl)silylmagnesium bromide, obtained in situ from tris(trimethylsilyl)silyllithium and magnesium bromide, reacts with acetone, pivalaldehyde, or 2,4,6‐trimethylbenzaldehyde to give the (1‐hydroxyalkyl)tris(trimethylsilyl)silanes (Me3Si)3SiC(OH)Me2 (1a), (Me3Si)3CH(OH)tBu (1b), and (Me3Si)3SiC(OH)Mes (1c), resp. After deprotonation with methyllithium in ether at ‐78°C 1a‐c eliminate trimethylsilanolate according to a modified Peterson mechanism to form transient silenes (Me3Si)2Si=CR1R2 (6a: R1 = R2 = Me; 6b: R1 = H, R2 = tBu; 6c: R1 = H, R2 = Mes). In the absence of trapping agents these silenes dimerize, 6a leading to the linear dimer 1‐isopropenyl‐2‐isopropyl‐1,1,2,2‐tetrakis(trimethylsilyl)disilane (7) and 6b giving the head‐to‐head cyclodimerization product (E)‐3,4‐di‐tert‐butyl‐1,1,2,2‐tetrakis(trimethylsilyl)‐1,2‐disilacyclobutane (8), whereas 6c in a very unusual cyclodimerization step affords (E)‐1,2,3,8a‐tetrahydro‐1‐mesityl‐5,7,8a‐trimethyl‐2,2,3,3‐tetrakis(trimethylsilyl)‐2,3‐disilanaphthalene (9). Compound 9 is the result of an unexpected [2 + 4] reaction, in which the silene formally acts as the monoene and – involving the aromatic substituent – simultaneously also as the diene. The reaction of 1a‐c with methyllithium in THF at low temperature initiates 1,3‐Si,O‐trimethylsilyl migrations leading to (trimethylsiloxy)‐[bis(trimethylsilyl)silyl]alkanes (Me3Si)2SiH–CR1R2OSiMe3 3a‐c. Reaction of 1a‐c with an excess of methyllithium, tert‐butyllithium, or phenyllithium, leads to trisilanes (Me3Si)2‐SiR3–CHR1R2 11a‐e, formed by the addition of the organolithium reagent to the Si=C bond of the transient silences 6a‐c. Deprotonation of 1b and 1c in the presence of 2,3‐dimethyl‐1,3‐butadiene gives the [2 + 4] cycloadducts 6‐tert‐butyl‐3,4‐dimethyl‐1,1‐bis(trimethylsilyl)‐1‐sila‐3‐cyclohexene (12a) and 6‐mesityl‐3,4‐dimethyl‐1,1‐bis(trimethylsilyl)‐l‐sila‐3‐cyclohexene (12b). For 8 and 9 the results of the X‐ray analyses are given.

High-valent organomanganese chemistry. 1. Synthesis and characterization of manganese(III) and -(IV) alkyls

A new manganese(IV) alkyl, the hexamethylmanganate salt [Li(tmed)] 2 [MnMe 6 ], has been prepared by treatment of MnMe 4 (PMe 3 ) 2 with methyllithium followed by addition of N,N,N',N'-tetramethylethylenediamine (tmed). Addition of excess methyllithium to Mn(acac) 3 followed by treatment with tmed gives the pentamethylmanganate [Li(tmed)] 2 [MnMe 5 ]. This trivalent species can also be obtained by a comproportionation reaction of the manganese(IV) complex [Li(tmed)] 2 [MnMe 6 ] with 1 equiv of the manganese(II) complex [Li(tmed)] 2 [MnMe 4 ] in diethyl ether. X-ray crystal structures of [Li(tmed) 2 ][MnMe 4 ] and [Li(tmed)] 2 [MnMe 6 ]

ChemInform Abstract: Electroorganic Chemistry. Part 105. A New Method of the Formation of the 9‐Azabicyclo(4.2.1)nonane Skeleton and Its Application to the Synthesis of (.+‐.)‐Anatoxin a.

Abstract1‐Methoxycarbonyl‐2,5‐dimethoxypyrrolidine (I) is coupled with 1‐ethoxy‐1‐trimethylsiloxy‐1,4‐pentadiene (II) in the presence of TiCl4 to give the cycloadduct (III) which is dechlorinated, saponified, and then treated with excess methyllithium (V), yielding the saturated acetyl derivative (VI).

Formation of a bridged vinylidenedi-iron complex by nucleophilic attack on a carbonyl ligand of [Fe2(CO)4(η-C5H5)2], and the synthesis and X-ray crystal structure of [(OC)3Fe((µ-Ph2PCHPPh2)FeH(CO)3

Reaction of [Fe2(µ-CO)2(CO)2(η-C5H5)2] with an excess of methyl-lithium in tetrahydrofuran followed by treatment with CF3CO2H at low temperatures affords a mixture of cis- and trans-[Fe2(µ-CCH2)(µ-CO)(CO)2(η-C5H5)2]. The isomers can be separated by column chromatography, and are thermally interconvertible. Reaction of the trans- vinylidenedi -iron complex with HBF4·Et2O affords the salt [Fe2(µ-CCH3)(µ-CO)(CO)2(η-C5H5)2][BF4], which deprotonates on treatment with NEt3 to form a mixture of cis- and trans-[Fe2(µ-CCH2)(µ-CO)(CO)2(η-C5H5)2]. In contrast, [Fe2(µ-CO)(µ-dppm)(CO)6](dppm = Ph2PCH2PPh2) is deprotonated by methyl-lithium to form an anionic species, which on protonation (CF3CO2H) affords the dinuclear iron complex [(OC)3Fe(µ-Ph2PCHPPh2)FeH(CO)3], characterised by n.m.r. spectroscopy and X-ray crystallography. Crystals are triclinic, space group P, Z= 4, in a unit cell with a= 10.504(3), b= 15.189(5), c= 19.552(5)A, α= 104.43(2), β= 103.04(2), and γ= 98.57(2)°. There are two independent molecules in the asymmetric unit, and the structure has been refined to R 0.073 (R′ 0.072) for 2 669 reflections with 2θ⩽ 40°(Mo-KαX-radiation) collected at 298 K. The two molecules have very similar geometries and contain a novel 1,2-diferra-3,5-diphosphabicyclo[2.1.0] pentane ring [mean separations within the ring system Fe–Fe 2.687(4), Fe–P 2.197(5) and 2.271(6), Fe–µ-C 2.15(2), and µ-C–P 1.79(2) and 1.76(2)A]. Both iron atoms are bonded to three carbonyl groups, but one of these ligands semi-bridges the metal–metal bond [Fe–C–O 152.6(14)°]. The hydrido-ligand was not located by the X-ray diffraction study but from potential-energy minimisation methods was calculated to be bridging the metal–metal bond, in accord with the 1H n.m.r. data for the compound.

Unexpected behavior of siloles toward organolithium reagents

The reaction of 5-trimethylsilyl-5-methyldibenzosilole (I) with an excess of methyllithium in THF afforded 5,5-dimethyldibenzosilole (II) in quantitati

Ortho-Metallated triphenylphosphine(2-diphenylphosphinophenyl) and related complexes of ruthenium(II): interaction of chlorohydridotris(triphenylphosphine)ruthenium(II) with methyl and trimethylsilylmethyl alkylating agents (Li, Mg, Zn); hydrido methyl and trimethylsilylmethyl complexes

The interaction of chlorohydridotris(triphenylphosphine)ruthenium(II), RuHCl(PPh3)3, with lithium, magnesium, and zinc alkyls has been studied.With trimethylsilylmethyl-lithium and methyl-lithium in diethyl ether and tetrahydrofuran, unstable, very reactive hydridoalkyls, RuH(R)(PPh3)2(S)2(R = CH2SiMe3 or Me, and S = Et2O or C4H8O) are formed. When warmed these compounds readily lose Me4Si or CH4via an ortho-metallation reaction of PPh3 to give the hydrido-(η3-2-diphenylphosphinophenyl) species, RuH(C6H4PPh2)(PPh3)2(S). With an excess of methyl-lithium in diethyl ether and with magnesium and zinc dimethyls, lithium-, magnesium-, and zinc-containing methyl complexes are obtained. The reaction of RuHCl(PPh3)3 with lithium alkyls has been monitored by n.m.r. spectroscopy of the intermediates, and the isolated complexes have been characterised and their stereochemistries derived from i.r. and 1H and 31P n.m.r. spectroscopy.The isolated and chemicallyanalysed new complexes are: RuHMe(PPh3)2(Et2O)2, RuHMe(PPh3)2(MeLiOEt2)2, RuMe(C6H4PPh2)(PPh3)2(Et2O), RuMe(C6H4PPh2)(PPh3)(MeLiOEt2)2, RuH(C6H4PPh2)(PPh3)2(Et2O), RuMe(C6H4PPh2)(PPh3)2(thf), {RuH(C6H4PPh2)(PPh3)2}2(Zn2Me3Cl), {RuH(C6H4PPh2)(PPh3)2}2[Mg2Me3Cl(Et2O)2].

The reactivity of cyclic germoxycarbene complexes of manganese and rhenium towards nucleophiles

Several acylate salts and noncyclic carbene complexes of manganese and rhenium, containing organogermanium ligands, have been prepared via the reactions of the cyclic germoxycarbene complexes of empirical formula Ph2GeM(CO)4COMe (M = Mn, Re) with the nucleophiles methyllithium or methoxide ion. In each case the observed product could be rationalized in terms of nucleophilic attack at germanium. Treatment of Ph2GeRe(CO)4COMe with methyllithium, followed by ethylation with aqueous Et3OBF4, afforded cis-Ph2MeGeRe(CO)4C(OEt)Me. The manganese analog of this product could be obtained if excess methyllithium were used in the first step. The use of a deficit of methyllithium, however, followed by ethylation, yielded cis-Ph2FGeMn(CO)4C(OEt)Me. Solution infrared spectra have indicated that lithium methoxide and lithium bromide impurities in the methyllithium are involved in this reaction. The reaction of Ph2GeMn(CO)4COMe with sodium methoxide is presumed to involve nucleophilic attack at germanium to give a methoxygermanium species. Subsequent treatment with aqueous tetraethylammonium bromide gave the hydroxygermanium complex, [cis-Ph2(HO)GeMn(CO)4C(O)Me][Et4N]. Ethylation of the same species with aqueous Et3OBF4 afforded cis-Ph2FGeMn(CO)4C(OEt)Me.

New synthesis of hexamethyltungsten(VI). The octamethyltungstate-(VI) lon

The interaction of tungsten hexachloride and trimethylaluminium in a hydrocarbon solvent followed by removal of chlorodimethylaluminium with an amine allows the synthesis of multigram quantities of hexamethyltungsten.Interaction of WMe6 with an excess of methyl-lithium in diethyl ether produces the anion [WMe8]2– which has been isolated as the thermally stable dioxan solvate Li2[WMe8]·(C4H8O2)2.

Zur Reaktionsweise von Enaminen mit Cyclopropenonen V. Einsatz von β‐Carbonyl‐enaminen

Diphenylcyclopropenone (10) was heated with five different β‐carbonyl‐enamines, namely 4‐pyrrolidino‐pent‐3 E‐en‐2‐one (12), 4‐dimethylamino‐pent‐3E‐en‐2‐one (13), 4‐dimethylamino‐but‐E‐en‐2‐one (14), 3‐dimethylamino‐1‐phenyl‐prop‐E‐en‐1‐one (15) and ethyl 3‐pyrrolidino‐isocrotonate (16). The resulting reactions were more sluggish than those of 10 with ordinary enamines. The main reaction (between 10 and 69% yield) was in all cases a ‘C, N‐insertion’. The major products were: from 12: an inseparable mixture of 4‐methyl‐6‐oxo‐2,3‐diphenyl‐hepta‐2E, 4E‐dienoic acid pyrrolidide (17) and its 2Z, 4E‐stereomer (18); from 13: 4‐methyl‐6‐oxo‐2, 3‐diphenyl‐hepta‐2E‐dienoic acid dimethylamide (19) and its 2Z, 4E‐stereomer (20); from 14: 6‐oxo‐2, 3‐diphenyl‐hepta‐2E, 4E‐dienoic acid dimethylamide (21); from 15: 6‐oxo‐2,3,6‐triphenyl‐hexa‐2E, 4E‐dienoic acid dimethylamide (22); and from 16: 5‐ethoxycarbonyl‐4‐methyl‐2, 3‐diphenyl‐penta‐2E, 4E‐dienoic acid pyrrolidide (23) and its 2Z, 4E‐stereomer (24). The constitutions of 17 to 24 were derived mainly from spectral properties.For these products the E‐configuration at the 4,5‐double bond was assigned on the assumption that the insertion of the side‐chain (cyclopropenone carbons) between the enamine carbon and nitrogen atoms occurred with retention of configuration, as had been concluded earlier. This was confirmed in the cases of 21 and 22 by the trans‐coupling between HC(4) and HC(5) in the 1HNMR. spectrum, the educts (14 and 15) having the E‐configuration. The configurational difference between the stereomeric products 17/18, 19/20 and 23/24 was, therefore attributed to the 2,3‐double bond. This was confirmed by aqueous acid treatment in the case of the pair 19/20 : The 2E‐configuration for 19 followed from its conversion to 4‐acetonyl‐4‐methyl‐ 2,3‐diphenyl‐isocrotonolactone (25) and the 2Z‐configuration of 20 by its conversion first to a mixture ol two diastereomers of (presumably) 1‐acetyl‐4‐dimethylaminocarbonyl‐2‐methyl‐3‐ phenyl‐l,4‐dihydronaphthalene (27a) and then, under more drastic conditions, to 6‐methyl‐11H‐benzo[a]fluorene (26).The structures of 25 and of 26 were derived from their spectral properties, and that of the 27a‐mixture was made probable by the plausibility of its intermediacy on the way to 26. A pathway for the conversion of 20 to 27a (scheme 3) and of the latter to 26 (scheme 4)is proposed.In the case of the reaction of 10 with 12, two stereomeric basic by‐products were isolated (combined yield 150/,). Their structures as traw‐ and cis‐4‐acetonyl‐4,5‐diphenyl‐3‐pyrrolidinocyclopent‐2‐en‐ones (30 and 31) were deduced from their spectral properties and from those of their hydrochlorides 32 and 33. The enamino‐ketone function was found to be resistant to a number of reagents, among which were excess sodium borohydride, which converted 30 to the secondary alcohol 34, and excess methyllithium, which converted 31 to the tertiary alcohol 35.A mechanism (called ‘rearrangement’) is proposed (scheme 5) for the formation of the enaminoketones (such as 30 and 31), which proceeds via the same ammonio‐enolate intermediate (36) which plays a role in the formation of the major products, the amides (such as 17 to 24). It is suggested (scheme 6) that the 3‐membered ring of the ammonio‐enolate 40 may open in three ways, one of which leads to the amides and another to the enamino‐ketones.