Dimethyl Tricyclo Research Articles

Reactivity increase of dienophiles by change of the ester substituents into the acid chlorides: cycloaddition reaction of the diacid chloride of 3,10-hexacyclo[10.2.1.15,8.02,11.03,10.04,9]hexadeca-6,13-diene-3,10-dicarboxylic acid with quadricyclane

Conversion of the ester substituents on the cyclobutene π-bond of dimethyl tricyclo[4.2.1.02,5]nona-3,7-diene-3,4-dicarboxylate to the corresponding acid chloride increases the cycloaddition reactivity toward quadricyclane so dramatically that the reaction temperature can be dropped from 180 °C (preparation of title 3,10-diester) to room temperature (preparation of the title 3,10-diacid chloride). The cycloadduct product, an acid chloride of the title ring system, is extremely docile and can be recrystallized unchanged from hot methanol.

Hinged bis -porphyrin scaffolds I. The synthesis of a new porphyrin diene and its role in constructing hinged porphyrin dyads and cavity systems

Norbornene building BLOCKs formed by the reaction of porphyrin 1,3-dienes with norbornadiene or dimethyl tricyclo[4.2.1.0 2,5]nona-2,7-diene-3,4-dicarboxylate were coupled with an ester-activated cyclobutene epoxide BLOCK to afford the first examples of hinged porphyrin-spacer-acceptor dyads. Similar dual coupling with a bis-(cyclobutene epoxide) formed doubly hinged POR-spacer-POR scaffolds separated by up to 16σ-bonds. The ability of the doubly hinged ZnPOR-16σ-ZnPOR scaffold to adopt cavity-shaped conformations was indicated by semiempirical AM1 calculations of these conformationally flexible bis-porphyrin scaffolds.

New systems for classical nitrosohalogenation of alkenes 1. Reactions of alkenes with ethyl nitrite in the presence of phosphorus halides and thionyl chloride

Studies of nitrosation of norbornene and norbornadiene derivatives and dimethyl tricyclo[4.2.2.02,5]deca-3,7-diene-9,10-cis-endo-dicarboxylate demonstrated that nitrosation of alkenes with EtONO-PHal3, EtONO-POHal3 (Hal = Cl or Br), and EtONO-SOCl2 systems can afford nitroso halides in high yields without the formation of by-products (ketones and oximes). The reactions with 5-substituted norbornenes are nonregioselective. The trans dimer of endo-5-trifluoromethyl-cis-exo-2-chloro-3-nitrosobicyclo[2.2.1]heptane was studied by X-ray diffraction.

Isoindole Cycloadditions. Part III: The Synthesis of "Windscreen Wiper" and Other N-Bridged Cavity Systems

The thermal addition of N-carbobenzyloxyisoindole (N-Z isoindole) 11a, generated by the reaction of 3,6-di(2-pyridyl)-s-tetrazine 9 with N-Z 7-azabenzonorbornadiene 8a, onto dimethyl tricyclo[4.2.1.02.5]nona-3,7-diene-3,4-dicarboxylate 17 occurred site selectively at the cyclobutene π-bond to form a stereoisomeric mixture of 1 : 1-adducts 18 and 19, in which the bent-frame isomer 19 was dominant (ratio 5 : 1). In contrast, N-benzyl tetrafluoroisoindole 11c reacted with 17 only under high-pressure conditions (14 kbar, RT, 4 days) to afford 1 : 1-adducts at the cyclobutene site, in which the extended-frame isomer 18c was dominant and the accompanying bent-frame product 19c reverted to starting materials soon after isolation. These same stereoselectivities were used to prepare "windscreen wiper" compound 28c having two mobile N-benzyl substituents attached to a rigid scaffold by the reaction of N-benzyl tetrafluoroisoindole 11c with tetramethyl tetracyclo[4.4.1.0.2,5.07.10]undeca-3,8-diene-3,4,7,8-tetracarboxylate 23. Cavity bis-(cyclobutene-1,2-diester) 6 reacted with N-benzyl tetrafluoroisoindole 11c twice over to produce cavity structure 36 with two O- and two N-benzyl bridges on the inner face, whereas the narrower cavity bis-alkene 32 stopped at the 1 : 1-addition stage. The dynamics of the Z-group in the dual adducts 26a–28a are discussed briefly and key adducts and cavity systems have been structurally evaluated by X-ray crystallography, VT NMR, and molecular modeling.

Reaction of mercury salts with dimethyl tricyclo [4.2.2.02,5]deca-3,7-diene-cis-endo-9,10-dicarboxylate in acetic acid

The reaction of dimethyl tricyclo[4.2.2.02,5]deca-3,7-diene-cis-endo-9,10-dicarboxylate with mercury salts Hg(OCOR)2 (R=CCl3, CF3, CH2Cl) in acetic acid yields a mixture of solvoadducts and products of addition of the anionic moiety of the reagent having thetrans-configuration. In the case of Hg(OCOCCl3)2,cis-solvoadduct was detected along with thetrans-isomer. The amount of the addition products is determined by the nature of the mercury salt and increases in the order Hg(OCOCH2Cl)2<Hg(OCOCCl3)2=Hg(OCOCF3)2. The reaction is assumed to involve contact and solvent-separated ion pairs.

Formation and Thermal Rearrangement of Dimethyl Tricyclo[6.2.2.01,7]dodeca‐2,4,6,9,11‐pentaene‐9,10‐dicarboxylates

AbstractThe high‐pressure reaction of 1‐methylazulenes 1 with excess of dimethyl acetylenedicarboxylate (ADM) in hexane at 30° and at pressures up to 7 kbar affords the tricyclic compounds 2 in reasonable‐to‐good yields (cf. Table 1). The crystalline compounds 2 decompose on melting into the starting materials and undergo rearrangement to the corresponding heptalene‐1,2‐dicarboxylates 6. The X‐ray crystal‐structure analyses of 2f and 2g (cf. Fig. 1) reveal the presence of a perfectly planar seven‐membered ring and comparably long C(1)–C(10) as well as C(1)–C(11) bonds (cf. Tables 2 and 3). The thermolysis of 2g in different solvents leads in aprotic media to the formation of the starting azulene 1g and, depending upon the polarity of the solvents, to varying amounts of the corresponding heptalene‐1,2‐dicarboxylate 6f (cf. Table 11). The formed amounts of 1g depends linearly on the ET values of the solvents (cf. Fig. 4). The same is valid for the thermolysis of 2g in protic media (cf. Table 10 and Fig.3). However, in these cases instead of the heptalene‐1,2‐dicarboxylate 6g, the corresponding (E)‐ and (Z)‐isomers of the 1‐(azulen‐1‐yl)ethene‐1,2‐dicarboxylates 7g are formed. The other tricyclic compounds 2 exhibit the same behavior on thermolysis in MeCN and BuOH (cf. Tables 8 and 9, resp.). The results show that the tricyclic compounds 2 undergo at temperatures up to 110° two competing reactions, namely heterolysis of the C(1)–C(10) bond, leading to the formation of heptalenes 6 in polar aprotic media, and the (E)‐ and (Z)‐ethene‐1,2‐dicarboxylates 7 in polar protic media, and concerted homolysis of the C(1)–C(10) and C(8)–C(9) bonds in the sense of a retro‐Diels‐Alder reaction in apolar media, yielding the starting azulenes and ADM, the amount of which decrease with increasing polarity of the solvent. The kinetic and activation parameters measured for 2g and the other tricyclic compounds 2 are collected in Tables 12–15. The tricyclic compounds 2a and 2b show in polar aprotic media (MeCN) a different behavior in that they form, instead of heptalenes, the corresponding 3,4‐dihydrocyclopent[cd]azulene‐1,2‐dicarboxylates 16a and 16b, respectively (Scheme 4). Experiments with [8‐2H]‐2a showed that these compounds are not formed via intramolecular H‐shifts (cf. Schemes 8 and 9).

Formation of dimethyl tricyclo[6.2.2.01,7]dodeca-2,4,6,9, 11-pentaene-9, 10-dicarboxylates from azulenes and dimethyl acetylenedicarboxylate under high pressure and thermal rearrangement of the tricyclic compounds into heptalene-1,2-dicarboxylates

Abstract It is shown that alkylated azulenes (see 1, 12, and 13) react with dimethyl acetylenedicarboxylate (ADM) in hexane under a pressure of 6–7 kbar already at 30° to yield the corresponding dimethyl tricyclo[6.2.2.01,7]dodeca-2,4,6,9, 11-pentaene-9, 10-dicarboxylates (see 14, 15, and 16). These compounds decompose in apolar solvents such as decane at temperatures > 50° mainly (>95%) to the starting materials. However, in polar solvents such as MeCN or DMF the formation of the corresponding dimethyl heptalene-1,2-dicarboxylates (see 2, 18, and 20) competes effectively with the decomposition into the starting materials. In polar and protic solvents such as EtOH or O(CH2CH2OH)2 instead of the heptalenes the corresponding (E)-and (z)-configurated dimethyl 1-(l′-azulenyl)-ethylene-l,2-dicarbox-ylates (see 17, 19, and 21) are formed. All experimental findings clearly show that the tricyclic compounds (14 to 16) are the crucial intermediates in the thermal formation of heptalenes from azulenes and ADM and t...

A short synthesis of dimethyl tricyclo[3.3.0.03,7]octane‐1,5‐dicarboxylate and its 3,7‐dimethyl derivative. A new route to the tricyclo[3.3.0.03,7]octane skeleton

Five-step syntheses of dimethyl tricyclo[3.3.0.03,7]octane-1,5-dicarboxylate (13) and its 3,7-dimethyl derivative 14 from the readily available cis-bicyclo[3.3.0]octane-3,7-diones 1 and 2, respectively, are described. The key-step implies the iodine oxidation of the bis-enolate derived from the corresponding dimethyl cis-bicyclo-[3.3.0]octane-3,7-dicarboxylates 11 and 12, thus being developed a new synthetic entry into the tricyclo[3.3.0.03,7]octane skeleton. Also, some attempts to synthesize diester 13 by using known methodology for the synthesis of compounds containing this tricyclic skeleton are described. Eine kurze Synthese von Tricyclo [3.3.0.03,7]octan-1,5-dicarbonsaure-dimethylester und seines 3,7-Dimethylderivats. Ein neuer Weg zum Tricyclo [3.3.0.03,7]octan-Gerust Die 5-stufige Synthese von Tricyclo[3.3.0.03,7]octan-1,5-dicarbonsaure-dimethylester (13) und seines 3,7-Dimethylderivats 14 ausgehend von den leicht zuganglichen cis-Bicyclo[3.3.0]octan-3,7-dionen 1 bzw. 2 wird beschrieben. Schlusselreaktion ist die Oxidation der Bis-enolate der cis-Bicyclo[3.3.0]octan-3,7-dicarbonsaure-dimethylester 11 und 12 mit Iod zum Tricyclo-[3.3.0.03,7]octan-Derivat 13 bzw. 14. Zusatzlich wird die Synthese des Diesters 13 nach bekannten Methoden versucht.

A new synthetic entry into the tricyclo[3.3.0.0 3,7] octane skeleton

A short synthesis of dimethyl tricyclo[3.3.0.0 3,7] octane-1,5-dicarboxylate, 13 , and its 3,7-dimethyl-derivative, 14 , by iodine oxidation of the bis-enolate derived from the corresponding dimethyl cis -bicyclo[3.3.0] octane-3,7-dicarboxylate, 11 or 12 , is described.

Attempts to develop new synthetic entries into the tricyclo[3.3.0.03,7]octane skeleton

The attempts to synthesize dimethyl tricyclo[3.3.0.03,7]octane-1,5-dicarboxylate, 1, and some related compounds by formation of a C3—C7 bond from appropriate bicyclo[3.3.0]octane derivatives, either through intramolecular C—H carbene insertion or by ketone-to-cyclopentanol photocyclization, are described. Two alternative syntheses for the key precursor, dimethyl cis-3-oxobicyclo[3.3.0]octane-1,5-dicarboxylate, 2, are included. Also, the formation of dimethyl 3-hydroxytricyclo[3.3.0.03,7]octane-1,5-dicarboxylate, 24, by reduction of dimethyl cis-3,7,dioxobicyclo[3.3.0]octane-1,5-dicarboxylate, 9, under Clemensen-like reaction conditions is reported.

Pinching group stabilization. The synthesis and thermal isomerization of 10-Oxapentacyclo[6.3.2.13,6.01,8.02,7]tetradeca-4,12-diene

Sensitized irradiation (benzophenone, 0�, N2, pyrex filter, medium pressure Hg lamp) of dimethyl tricyclo[4.2.1.02,5]nona-3,7-diene-3,4-dicarboxylate (11) in (E)-1,2-dichloroethene yielded a mixture of 1 : 1 adducts (13) and (14) by site selective [2 π+2 π] cycloaddition at the cyclobutene π-bond. Reduction of the (Z)-dichloro isomer(13) with lithium aluminium hydride formed the related diol (16) which is the immediate precursor to the cyclic ether (18). Dechlorination of (18) with zinc in ethanol forms the title diene (19). Thermolysis of the polycyclic diester (20) affords the fragmentation products cyclopentadiene and dimethyl benzene-1,4-dicarboxylate. In contrast, the title compound (19) containing the cyclic ether ring was more stable and yielded the novel isomer (28) as the major product only upon flash vacuum pyrolysis at 560�(1.5 × 10-2 Torr). This difference in behaviour is attributed to a pinching group effect exerted by the cyclic ether present in (19).

Electrophilic additions to strained alkenes. II. The reaction of benzeneselenenyl chloride with tricyclo[4.2.2.02,5]deca-3,7-diene derivatives

The reactions of benzeneselenenyl chloride with three derivatives of tricyclo[4.2.2.02,5]deca-3,7-diene have been investigated in four solvent systems: methylene chloride, acetic acid, acetic acid/LiClO4, and methanol. Under conditions of kinetic control only products of exo–anti attack upon the cyclobutene moiety are isolable when the solvent system is methylene chloride or acetic acid. This observation also holds in acetic acid/LiClO4 except in the case of dimethyl tricyclo[4.2.2.02,5]deca-3,7,9-triene-7,8-dicarboxylate where the major product is that of cross-bonding with solvent incorporation. In methanol products of solvent incorporation, transannular cross-bonding and lactonization (where possible) are observed. A general mechanistic scheme is proposed to account for these observations in accord with earlier results for the analogous arenesulphenylations.

Stereochemistry of electrophilic addition to dimethyl tricyclo[4,2,2,0 2,5] Deca-3,7-diene-9,10-dicarboxylate. Molecular structure of Hg(OAc) 2-addition product

The molecular structure of the trans addition product of Hg(OAc) 2 to diester 1 has been determined by X-ray diffraction (represented by formula 3 ) which leads to a revision of previously claimed cis -additions in this series.

ChemInform Abstract: DOUBLE DIELS‐ALDER REACTIONS OF COUMALIC ACID WITH 1,3‐DIENES

AbstractDie Pyroncarbonsäure (I) reagiert mit acyclischen Dienen in einer doppelten Diels‐Alder‐Reaktion nach Umsetzung mit Diazomethan zu den tricyclischen Verbindungen (II), deren Struktur durch Reduktion bzw. Hydrierung gesichert wird.

Double Diels-Alder Reactions of Coumalic Acid with 1,3-Dienes

Abstract Thermal reaction of coumalic acid with 1,3-butadienes gave after diazomethane treatment dimethyl tricyclo[3.2.1.02,7]oct-3-ene-2,4-dicarboxylate via double Diels-Alder reaction. This represents the simplest synthesis of such a tricyclic system. The reaction with cyclopentadiene was also studied.

Synthesis of 1,2-acenaphtho-3,8-disubstituted-derivatives of cyclo-octatetraene

Acecyclone and related cyclopentadienones 11 react with dimethyl tricyclo[4.2.0.0 2,5]deca-3,7,9-triene-7, 8-dicarboxylate 1 in refluxing xylene to afford the cyclo-octatetraenes 12, via a sequence involving [4+2]π-cycloaddition, cheletropic loss of carbon monoxide, extrusion of dimethyl phthalate by [4+2]π-cycloreversion, and finally valence isomerisation by retro-6π electrocyclisation. NMR evidence indicates that the products 12 contain rigid, bond-fixed, non-planar cyclo-octatetraene rings.

ChemInform Abstract: THE PREPARATION OF TRICYCLO(4.2.1.02,5)NONA‐3,7‐DIENES BY CYCLOADDITIONS ONTO 3,4‐DISUBSTITUTED CYCLOBUTENES. SPECIFICITIES IN THE DIELS‐ALDER REACTION

AbstractAus dem Dien (I) und dem Dienophil (II) entstehen das exo, anti‐Addukt (III) (80% des Reaktionsgemisches) und das endo, anti‐Addukt (IV), das bei höherer Temperatur unter Decarbonylierung in das Bicyclooctadien (V) übergeht.

The preparation of Tricyclo[4,2,1,02,5]nona-3,7-dienes by cycloadditions onto 3,4-disubstituted cyclobutenes. Specificities in the Diels-Alder reaction

The reaction between cis-3,4-dichlorocyclobutene and 2,5-dimethyl-3,4- diphenylcyclopenta-2,4-dienone forms a mixture of exo,anti (28) and endo,anti adducts (27) with the former predominating. At higher temperatures the endo,anti adduct (27) undergoes smooth decarbonylation to form cis-7,8-dicldoro-2,5-dimethyl-3,4-diphenylbicyclo[4,2,0]octa- 2,4-diene. The stereochemistry of each adduct was determined by a combination of spectral (especially p.m.r.) techniques and chemical trans-formations. Intramolecular nucleophilic displacements and electrophilically induced cyclizations have been instrumental in determining stereochemical relationships. Similar cycloadditions involving 1,2,3,4-tetrachloro-5,5-dimethoxycyclopenta-1,3-diene and 1,4-dimethyl-2,3-diphenylcyclopenta-1,3-diene as the diene components and cis-3,4-dichlorocyclobutene or dimethyl tricyclo[4,2,2,02,5]deca- 3,7,9-triene-7,8-dicarboxylate (10) as dienophiles have been studied and the stereoselectivities determined. A combination of steric and secondary orbital effects have been proposed to account for the observed stereospecificities1. A PMO-based treatment is used to account for the perispecificity of (10) and related alicyclic polyenes.

Heterocycles by cycloaddition. Part 5. Preparation of 7,9-diheteratricyclo[4.2.1.02,5]non-3-en-8-one derivatives from mesoionic compounds

Cycloaddition of a mesoionic dithiolone or thiazolone (1) with dimethyl tricyclo[4.2.2.02,5]deca-3,7,9-triene-7,8-dicarboxylate (2) occurred at the cyclobutene ring. Thermal fragmentation of the adducts (3) or the corresponding S-oxides (6) gave dimethyl phthalate and the title diheteratricyclononenone derivatives (4) or their S-oxides (7).

Molecular design by cycloaddition reactions. Part 32. Transannular cyclization of tricyclo[4.2.2.02,5]deca-3,7-diene derivatives by oxypalladation

Reactions of dimethyl tricyclo[4.2.2.02,5]deca-3,7-diene-9,10-dicarboxylate derivatives with palladium(II) acetate, chloride, and nitrate have been investigated. The products were identified by spectral means and chemical transformations. Mechanisms for their formation are discussed.