Trisubstituted Compounds Research Articles

A stereoselective synthesis of bromohomoallylic derivatives

Perusal of the current chemical literature reveals an expanding interest in the stereoselective synthesis of trisubstituted ethylenic compounds Such interests are easily grasped since stereochemically pure olefins are often found in various natural products such as hormones, sex attractants, terpenes and marine products. We now report a new rearrangement of the bromocyclopropylcarbinol 2 leading to the formation of the stereochemically pure E-isomer of bromohomoallylic derivatives 6 or z. These compounds might be valuable intermediates in synthesis of trisubstituted olefins of non ambiguous stereochemistry. Gem-dibromocyclopropylcarbino12 1 is obtained in gcod yield by &LLu3 mocarbene addition to the appropriate allylic alcohol (phase transfer method) . Subsequent reduction by Zn/AcOH4 is remarkably stereoselective resulting in a predominance of the cis-bromine substituted product 2 (overall yield 90 %). Stereochemistry of 2 and 2 is confirmed by oxidation (Jones reagent, 5 quantitatively) to known bromocyclopropylketones 4 and 5 .

13C n.m.r. spectra of some polychloroalkenes

Abstract13C n.m.r. spectra have been measured for thirty‐two polychloroalkenes including (i) monosubstituted compounds CH2CHCClnH2−nX, where X stands for H, Cl, alkyl, and trisubstituted alkenes CCl2CHAlk, none of which form geometric isomers; (ii) disubstituted compounds RCHCHR′; (iii) and (iv) trisubstituted compounds of the types RCClCHR′ and CHClCClR, respectively. Compounds (ii) to (iv) represent either individual isomers or mixtures of the Z and E forms. In the case of compounds (ii) and (iii), the ordering of chemical shifts is δE > δZ for the sp2‐carbon atoms and δE < δz for the adjacent tetrahedral ones. On the contrary, the signals of the sp2‐carbon atoms of compounds (iv) obey the rule δE < δz. The effect of vinyl and allyl groups as substituents on the 13C chemical shifts of chlorine‐containing groups is discussed. The dependence of the sp2‐carbon spin–spin coupling constants J(13C1H) on the number of chlorinated substituents in the molecule is also considered.

Silicium-stickstoff-fluorverbidungen: V. Darstellung neuer silylaminofluorsilane

Compounds of the composition RR′SiFNR″Si(CH 3) 3 (R = H, F, CH 3, C 2H 5, C 3H 7, C 2H 3, C 6H 5, C(CH 3) 3; R = F, CH 3, C 6H 5; R″ = CH 3, C(CH 3) 3, Si(CH 3) 3) are obtained by the reaction of silicontetrafluoride or organo-substituted silicon-fluorides with the lithium salts of alkylsilylamines in a molar ratio of 1 1 . The disubstituted compounds RSiF(NR′Si(CH 3) 3) 2 (R = H, F, CH 3, C 2H 3, C 6H 5; R′ = CH 3, C(CH 3) 3) result when the reactants are in a 1 2 molar-ratio. Likewise the unsymmetrical siliconfluorsilylamines of the formulae F 2Si(NRSi(CH 3) 3) (NR′Si(CH 3) 3) (R = CH 3, R′ = C(CH 3) 3), as well as the trisubstituted compounds FSi(NCH 3Si(CH 3) 3) 3 and FSi(NCH 3Si(CH 3) 3) 2(N(Si(CH 3) 3) 2) were made. By reacting phenyltrifluorsilane with dialkylamines ( 1 2 ) C 6H 5SiF 2NR 2(R = CH 3, C 2H 5) was obtained. The IR-, mass-, 1H and 19F NMR spectra of the above-mentioned compounds are reported.

ChemInform Abstract: SUBSTITUENT EFFECTS ON THE PROTON SPIN‐SPIN COUPLING OF BENZENES WITH SIDE‐CHAIN INTERACTING GROUPS

Abstract Sixty MHz NMR proton spectra of 15 2,4-substituted benzaldehydes and 12 methylbenzenes dissolved in different solvents have been accurately analyzed. Substituent effects on the coupling constants have been determined and have been found to be additive in those trisubstituted compounds where there are neither internal hydrogen bonds or strong interacting groups present.

Substituent effects on the proton spin-spin coupling of benzenes with side-chain interacting groups

Sixty MHz NMR proton spectra of 15 2,4-substituted benzaldehydes and 12 methylbenzenes dissolved in different solvents have been accurately analyzed. Substituent effects on the coupling constants have been determined and have been found to be additive in those trisubstituted compounds where there are neither internal hydrogen bonds or strong interacting groups present.

Application of the Hammett relationship to a series of tetrasubstituted thiophens. Kinetics of piperidino-debromination of some 2-bromo-3-nitro-5-X-thiophens and 2-bromo-4-methyl-3-nitro-5-X-thiophens in methanol

The rates of piperidino-debromination of some 2-bromo-3-nitro-5-X-thiophens and 2-bromo-4-methyl-3-nitro-5-X-thiophens in methanol have been measured. The results indicate that the Hammett relationship can be applied to the tetrasubstituted as well as to the trisubstituted compounds. The kinetic data for 2-bromo-4-methyl-3-nitro-5-X-thiophens represent the first good fit of the Hammett equation for a series of ortho-tetrasubstituted compounds. This is possible with fully substituted thiophens because the geometry of the 5-membered ring lowers steric interactions which in a 6-membered ring (e.g. benzene) are known to be very large.

Metal carbonyl chemistry. Part VII. The reaction of ligands with phenylpentacarbonylmanganese

The preparation of phenyl- and benzoyl-manganese carbonyl complexes from the reactions of the ligands 1-ethyl-4-phospha-3,5,8-trioxabicyclo[2,2,2]octane, P(OCH2)3CEt, triphenylphosphine, or triphenyl phosphite with phenylpentacarbonylmanganese are described. The phosphite ligands lead to the formation of mono-, di-, and tri-substituted compounds of the type PhCOMn(CO)4L, PhMn(CO)4L, PhCOMn(CO)3L2, PhMn(CO)3L2, [where L = P(OPh)3 or P(OCH2)3CEt], and PhCOMn(CO)2[P(OCH2)3CEt]3 depending on the reaction conditions employed. The reaction with triphenylphosphine gives cis-PhMn(CO)4PPh3, although some evidence was obtained for the intermediate formation of the unstable compound PhCOMn(CO)4PPh3. The stereochemistry of these compounds is discussed on the basis of their dipole moments, and infrared and 1H n.m.r. spectroscopic measurements.

Synthesis of organoelement derivatives of barenes (carboranes)

The preparation of organoelement derivatives of barenes by alkylation (barenylation) of various mercury, silicon germanium, tin, phosphorus, arsenic and antimony halides is described. Attempts to prepare the tetrabarenyltin and tribarenylphosphine compounds failed because of steric hindrance. The increase in size of the arsenic and antimony atoms allowed the tri-substituted compounds to be prepared.

Organoboron heterocyclic compounds

1. The reactions of organomagnesium compounds of furan and 2-methylfuran with potassium fluoborate were investigated. 2. For the first time, heterocyclic trisubstituted organoboron compounds were prepared (derivatives of 2-methylfuran, thiophene, and selenophene).

The Near Ultraviolet Absorption Spectra of 1,4 Bis-(Trifluoromethyl)Benzene and 1,3,5 Tris-(Trifluoromethyl)Benzene

The vapor absorption spectra of 1,4 C6H4(CF3)2 and 1,3,5 C6H3(CF3)3 have been obtained with a Bausch and Lomb Littrow spectrograph. Corresponding solution spectra were obtained with a Beckman DU spectrophotometer. Oscillator strengths f were found to be 12.0×10−3 and 2.1×10−3 for the para di- and tri-substituted compounds, respectively. Both of the vapor spectra are diffuse with the bands of the 1,3,5 compound showing extreme diffuseness. The 0,0 band of the 1,4 bis-(trifluoromethyl)benzene is located at 37460 cm−1. Progressions and combinations involving the upper state frequencies of 210, 770, and 1020 cm−1 are observed. The 210 and 1020 values are correlated with the observed ground state values of 240 and 1070 cm−1, and these are associated with totally symmetric vibrations. The 1,3,5 tris-(trifluoromethyl)benzene spectrum is interpreted as a ``forbidden'' one and the bands at 38670 and 38070 cm−1 are assigned as 0,1 and 1,0 bands, respectively. Rough calculations show the 0,0 band to be shifted about 300 cm−1 toward the violet relative to the benzene spectrum.

Structure of the Nitro Group

THE usual formula given to the nitro group is containing a co-ordinate link1, and it is sup-ported by the parachor evidence2. On account of this dissymmetry, both the compounds 1-4-dinitrobenzene and 1-3-5-trinitrobenzene should possess finite electric dipole moments. Also studies in benzene3 and in naphthalene4 have resulted in moments of 0·6 and 0·8 Debye units being ascribed to the di- and tri-substituted compounds respectively.