Thermal and photochemical decomposition of cis- and trans-3,5-diphenyl-1-pyrazoline

The decomposition mechanism of the title compounds 8c and 8t is discussed. Dibenzylic 1,3-biradicals are suggested as intermediates.     

Some perfluoroalkyl grignard reagents and their derivatives

Some perfluoroalkyl Grignard reagents have been prepared in high yields through halogen-metal exchange reactions between perfluoroalkyl iodides (R_fI) and EtMgBr. Derivatization with Me₃SiCl gave satisfactory yields of the corresponding silylated products in THF. However, ether was a very poor solvent for reaction of R_fMgBr with these chlorosilanes. The exchange reaction between R_fI and EtMgBr was nearly quantitative in ether as evidenced by high yields of the 1-hydroperfluoroalkanes upon hydrolysis, but the major production from the attempted silylation in ether was a trans- vinyl bromide [1], i. e.

Spectral data are presented for several new compounds.     

Silicon-carbon unsaturated compounds. 77. Thermal behavior of cis- and trans-1-silacyclobut-3-ene formed from pivaloyl[tert-butylbis(trimethylsilyl)]silane and tert-butylacetylene

The reaction of tert-butylbis(trimethylsilyl)silyl potassium with pivaloyl chloride gave pivaloyl[tert-butylbis(trimethylsilyl)]silane (1) in 89% yield. The cothermolysis of 1 with tert-butylacetylene at 140 °C for 24 h produced the mixture consisting of cis- and trans-1,2,3-tri(tert-butyl)-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclobut-3-ene (cis-2 and trans-2) in a ratio of 0.7: 1, in 88% combined yield. The thermolysis of the mixture, cis-2 and trans-2, at 250 °C for 24 h proceeded to give trans-1,2,4-tri(tert-butyl)-1-(trimethylsiloxy)-2-(trimethylsilyl)-1-silacyclobut-3-ene (4) as a single product in 96% yield. Similar treatment of cis- and trans-2 at 190 °C for 15 h afforded silylcyclopropene 3 quantitatively, which underwent further isomerization at 250 °C to give trans-1-silacyclobut-3-ene 4 in quantitative yield.     

Synthesis and some properties of 1H-1-benzazepines

1H-1-Benzazepines were synthesized by thermal ring opening of 2a,7b-dihydrocyclobut[b]indoles. The thermal and photochemical behavior of the 1H-1-benzazepines is also described.     

Synthesis and odor of optically active trans-2,2,6-trimethylcyclohexyl methyl ketones and their related compounds

The synthesis characterized by cationic olefin cyclizations accomplished using ketone enol esters and odor of novel (1R,6S)- and (1S,6R)-2,2,6-trimethylcyclohexyl methyl ketones (5) are described. The stereoselective syntheses of (E)-(1R,6S)- and (E)-(1S,6R)-1-(2,2,6-trimethylcyclohexyl)-2-buten-1-one (6) and (1R,6S)-ethyl 2,2,6-trimethylcyclohexylcarboxylate (7), useful raw materials for flavor and fragrance, starting from the (1R,6S)- and (1S,6R)-5 are also described.     

Stereoselective synthesis of cis- and trans-3-fluoro-1-phenylcyclobutyl amine

A stereoselective approach to the synthesis of cis- and trans-3-fluoro-1-phenylcyclobutylamine has been developed. Excellent stereoselectivity was obtained by the reduction of the appropriately substituted cyclobutanone to give either cis- or trans-isomers of 3-hydroxyl-1-phenylcyclobutylamine, which was stereoselectively converted to the 3-fluoro derivative.     

Synthesis and reactivity of trans-2-aryl-3-chloroazetidines

Several trans-2-aryl-3-chloroazetidines were synthesized in a stereoselective way by reduction of the corresponding β-lactams, which were formed by a Staudinger reaction using different benzaldimines and chloroketene. The resulting chloroazetidines proved to be excellent building blocks for the synthesis of different 3-substituted azetidines through nucleophilic substitution of the chlorine by different carbon, nitrogen, sulfur and oxygen nucleophiles in good to high yields. Since these substitution reactions took place with retention of stereochemistry, the intermediacy of bicyclic azonio[1.1.0]bicyclobutanes is proposed.     

Stereodivergent reduction of enelactams embedded in hexahydroindoles. Synthesis of trans-3-substituted-cis-3a-methyloctahydroindoles

A stereodivergent synthesis of cis- and trans-octahydroindole derivatives from the ethylene acetal of methyl 1-benzyl-3a-methyl-2,5-dioxo-2,3,3a,5,6-hexahydro-1H-3-indoleacetate is reported. Under ionic reduction conditions the enamide group was reduced to afford a trans-ring fused product, while a hydrogenation process led to the formation of a cis-ring fused lactam, which was transformed into a building block for daphniphyllum alkaloid synthesis after an epimerization at C-3.     

Synthesis of trans-vaccenic acid and cis-9-trans-11-conjugated linoleic acid

The preparation of the monounsaturated fatty acid, trans-vaccenic acid 4 (TVA), using both Wittig and one-pot Julia-Kocieński olefination protocol, was achieved in good yield. Similarly a Wittig approach was employed for the stereoselective synthesis of cis-9-trans-11-conjugated linoleic acid 2 from trans-2-nonenal and (8-carboxyoctyl)triphenylphosphonium bromide 12.     

Synthesis and characterization of aliphatic unsaturated polyesters from trans-4-octene-1,8-dioic and trans-3-hexene-1,6-dioic acids

The influence of the double bond on the thermodynamic parameters, T_m, ΔH_m and ΔS_m of some unsaturated aliphatic polyesters has been found to depend on the number of —CH₂— groups separating the double bond from the ester linkage. Thus, T_m's of the polyesters derived from trans-4-octene-1,8-dioic acid (OD) are lower than those for the corresponding saturated polyesters; no such effect has been observed by comparing T_m's of polyesters derived from trans-3-hexene-1,6-dioic acid (HD) and adipic acid respectively. X-ray investigation has shown, for polyesters of the OD series, the presence of the two polymorphic forms.     

Organophosphorus compounds XVI. Synthesis of some novel 2,3-dihydro-1H-1,2-benzazaphosphole 2-oxides and -sulphides

Several derivatives of 2,3-dihydro-1H-1,2-benzazaphosphole, a new class of benz-fused NP heterocycle, have been synthesised by thermal and DCC-promoted NP ring closure from zwitterionic intermediates.     

Synthesis of trans-4-aryl-3-(3-chloropropyl)azetidin-2-ones and their transformation into trans- and cis-2-arylpiperidine-3-carboxylates

Treatment of arylmethylideneamines with 5-chloropentanoyl chloride in benzene in the presence of 2,6-lutidine afforded novel trans-4-aryl-3-(3-chloropropyl)azetidin-2-ones in good yields. The latter 3-(3-chloropropyl)-β-lactams were transformed selectively into trans-methyl 1-alkyl-2-arylpiperidine-3-carboxylates in high yields and purity upon subsequent treatment with hydrogen chloride in methanol and triethylamine in dichloromethane. These trans-1-alkyl-2-arylpiperidine-3-carboxylates were easily converted into either their cis-isomers upon treatment with hydrazine monohydrate in methanol, or into the corresponding piperidine-1,3-dicarboxylates by reaction with alkyl chloroformates in benzene. Finally, 3-(3-chloropropyl)-1-(4-methoxybenzyl)-4-phenylazetidin-2-one was transformed into the corresponding trans-1-tert-butoxycarbonyl-3-(4-methoxybenzylcarbamoyl)piperidine via a three-step sequence in a good overall yield.     

Stereoselective synthesis of highly substituted trans-2,3-dihydrofuran and trans-1,2-cyclopropane derivatives containing sulfonyl groups

trans-2,3-Dihydrofuran derivatives 3 and trans-1,2-cyclopropane derivatives 4 were prepared with high chemoselectivity and moderate overall chemical yield by the reaction of α,β-unsaturated sulfones 1 with arsonium bromides 2 in the presence of potassium carbonate. The structures of products obtained were identified by IR, MS, ¹H NMR, elemental analysis, and X-ray diffraction analysis.     

Synthesis and structure of some cis-and trans-myrtanylstannanes

Enantiomerically pure cis- and trans-myrtanylstannanes cis-MyrSnPh₃ (1), trans-MyrSnPh₃ (2), cis-MyrSnPh₂Cl (3), trans-MyrSnPh₂Cl (4), cis-MyrSnPhCl₂ (5), trans-MyrSnPhCl₂ (6), cis-MyrSnCl₃ (7), trans-MyrSnCl₃ (8) were synthesized and fully characterized by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. The molecular structures of 1, 3, 6, 7, and [trans-MyrSn(OH)Cl₂ · H₂O]₂ (8a) a hydrolysis product of 8, were determined by X-ray crystallography.     

Fluorohalogeno compounds. I. The grignard reaction of some fluorohalogenoethanes

An extension of the scope of the Grignard reaction of fluorinated compounds is reported. Fluorohalogenoethanes of the general formula CF₃CXYZ ( X = F,Cl,Br ; Y,Z = Cl,Br ) were found to undergo smoothly the metal-halogen exchange reaction with alkyl- or aryl-magnesium halides at low temperature to yield organometallic compounds CF₃CXYMgHal. The Grignard compounds were reacted with a series of aldehydes and ketones to give the corresponding alcohols in good to moderate preparative yields.     

Synthesis of aromatic organoindium compounds of the glass Ar3In by means of grignard reagents

Conclusions A method was developed for preparing organoindium compounds of the class Ar₃In by means of Grignard reagents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2410–2412, October, 1968.     

Condensation of salicylnitrile with some α-halo carbonyl compounds

3-Aminobenzofuran derivatives were obtained by condensation of salicylnitrile and 5-bromosalicylnitrile with -monochloroacetic acid derivatives and -halo ketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1171–1173, September, 1974.     

Reaction of perfluoroalkyl grignard reagents with phosphorus trihalides: a new route to perfluoroalkyl-phosphonous and -phosphonic acids

The reaction of perfluoroalkyl Grignard reagents with phosphorus(III) halides was explored. In the process a new convenient, one-pot, high yield method for the synthesis of (perfluoroalkyl)phosphonic acids has been developed. Perfluoroalkyl Grignard reagents react with phosphorus trichloride or phosphorus tribromide to form (perfluoroalkyl)phosphonous dihalides. Hydrolysis gives the corresponding (perfluoroalkyl)phosphonous acids. Oxidation of the phosphonous acids with H(2)O(2) produces (perfluoroalkyl)phosphonic acids in 60-78% overall yields, based on the corresponding perfluoroalkyl iodide. The X-ray crystal structures of the toluidinium salts, [MeC(6)H(4)NH(3)](2)[C(2)F(5)PO(3)] and [MeC(6)H(4)NH(3)][C(8)F(17)P(O)(2)OH], are reported.     

New stereoselective syntheses of cis- and trans-2-methyl-4-arylpiperidines

A stereoselective approach has been developed for the synthesis of cis- and trans-2-methyl-4-arylpiperidines from a common intermediate. The Ni-catalyzed hydrogenolysis of N-Boc-2-methyl-4-aryl-4-piperidinols, obtained by addition of organometallic reagents on N-Boc-2-methyl-4-piperidone, afforded the trans derivatives with up to 95% selectivity whereas the corresponding cis isomers were obtained in the presence of palladium catalysts.