Photocycloaddition of 2-Cyanocycloalk-2-Enones to 2, 3-Dimethylbut-2-Ene

Irradiation of 5,5-dimethyl-6-oxocyclohex- l-ene- l-carbonitrile ( 1 ) in the presence of 2,3-dimethylbut-2-ene afforded 3,3,4,4,7,7-hexamethyl-3,4,4a,5,6,7-hexahydroindeno[1,7-c,d]-],2-oxazole (3) in nearly quantitative yield. In contrast, 4,4-dimethyl-5-oxo-cyclopent-l-ene-l-carbonitrile ( 2 ) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7-hexamethyl-2-oxo-bicyclo[3.2.0]heptane-l-carbonitrile ( 4 ) and trans-3,3-dimethyl-2-oxo-5-(2,3-dimethylbut-3-en-2-yl)cyclopentane-l-carbonitrile ( 5 ), respectively.     

Reaction with Aqueous Alkali of Diammonium Salts with a 1,1-Dimethylbut-2-yne-1,4-diyl Common Group

Quaternary ammonium salts with a 1,1-dimethylbut-2-yne-1,4-diyl common group react with aqueous alkali with intermediate formation of 1,2- rather than 1,4-cleavage products. When both nitrogen atoms bear allylic groups, rearrangement-cleavage-substitution occurs to give methyl isopropyl ketones. Salts with two 3-methylbut-2-en-1-yl groups cleave isoprene.     

New atropoisomeric alkenylphenylglycine derivatives: Synthesis of (5R*)- and (5S*)-isomers of (1R*,3aR*,4S*,11S*)-3a,5,9,11-tetramethyl-4,5-dihydro-3aH-1,4-methano[1,3]oxazolo[3,2-a]quinolin-2-one

We synthesized methyl ester of N-(1-methylbut-2-en-1-yl)-N-phenylglycine which underwent acid catalyzed aromatic amino Claisen rearrangement to provide methyl-N-[2-(1-methylbut-2-en-1-yl)phenyl]glycinate. A mixture of syn- and anti-atropisomeric methyl-N-acetyl-N-[4-methyl-2-(1-methylbut-2-en-1-yl)phenyl]glycinates was obtained either by the reaction of this ester with acetyl bromide or by the reaction of the sodium salt of N-acetyl-2-(1-methylbut-2-en-1-yl)-4-methylaniline with methyl bromoacetate. Upon saponification of the synthesized ester mixture the syn-atropisomer of N-acetyl-N-[4-methyl-2-(1-methylbut-2-en-1-yl)phenyl]glycine was isolated by fractional crystallization. Treatment of the obtained acids with acetic anhydride, ethyl chloroformate, dicyclohexylcarbodiimide or isopropenylacetate leads to compounds of 4,5-dihydro-3aH-methano[1,3]oxazolo[3,2-a]quinolin-2-one structure.     

Two new sesquiterpenoids and two new prenylated phenylpropanoids from Illicium fargesii, and neuroprotective activity of macranthol

Two new seco-prezizaane-type sesquiterpenoids 1, 2 and two new prenylated phenylpropanoids 4, 5 were isolated along with 15 known compounds from Illicium fargesii. The structures of 1, 2 were elucidated as 10-O-(E)- and 10-O-(Z)-cinnamoyl-2-oxo-6-deoxyneoanisatin by analysis of spectroscopic data and by comparison of their NMR data with those of previously reported 2-oxo-6-deoxyneoanisatin (3), respectively, whereas the structures of 4, 5 were identified as 4-allyl-2-(3-methylbut-2-en-1-yl)phenol and 4-allyl-2-(2-methylbut-3-en-2-yl)phenol, respectively, on the basis of spectroscopic data. Among the isolated compounds, macranthol (7) was found to have neuroprotective activity at 5--10 microM in rat cortical neurons cultured in DMEM/N2 medium.     

Synthesis,Characterization, and Antioxidant Properties of Novel 1-(4-Aryl-1,3-thiazol-2-yl)-2-{[1-(3-methylbut-2-en-1-yl)-1H-indol-3-yl]methylidene}hydrazines

Russian Journal of Organic Chemistry - A series of novel 1-(4-aryl-1,3-thiazol-2-yl)-2-{[1-(3-methylbut-2-en-1-yl)-1H-indol-3-yl]methyli­dene}hydrazines were synthesized and properly...     

Formation of 2,3,4,5,6-pentafluorophenylcarbonimidoyl dichloride by copyrolysis of 2,3,4,5,6-pentafluoroaniline with chloroform

The pyrolysis of pentafluorophenyl 2-methylprop-2-enyl ether (XIII) at 310° gave 4-(2-methylprop-2-enyl)-2,3,4,5,6-pentafluoro-2,5-cyclohexadienone (XVI) (46%), while at 410° a mixture of 1-fluorovinyl 2,3,4-trifluoro-5-methylphenyl ketone (XVIII) (30%) and 2,5β,6,7,7aβ-pentafluoro-3aβ-methyl-3aβ,4,5,7a-tetrahydroinden-1-one (XXI) (22%) was formed from the possible internal Diels-Alder adducts (XVII) and (XX) respectively (Scheme 6). Pentafluorophenyl 2-methylbut-3-en-2-yl ether (XVI) decomposed under mild conditions (70°) to give pentafluorophenyl 3-methylbut-2-en-1-yl ether (XXII), pentafluorophenol and 2-methyl-1,3-butadiene possibly via an ion pair intermediate (Scheme 7).     

C2 molecule: formation from bromoacetylene and reactions with cyclohexene or 2,3-dimethyl-2-butene

The C₂ molecule (1,2-ethynediyl) has been prepared by dehydrohalogenation of 1,2-dibromoethylene with an excess of potassium tert-butoxide in 2,3-dimethyl-2-butene as the solvent and the reagent. The major products of this reaction were 2,3-dimethylbut-3-en-2-ol and dibromoacetylene.     

Pyrolyses of pentafluorophenyl 2-methylprop-2-enyl ether. Reactions proceeding via internal diels-alder reactions, and the contrasting thermolysis of pentafluorophenyl 2-methylbut-3-en-2-yl ether

The pyrolysis of pentafluorophenyl 2-methylprop-2-enyl ether (XIII) at 310° gave 4-(2-methylprop-2-enyl)-2,3,4,5,6-pentafluoro-2,5-cyclohexadienone (XVI) (46%), while at 410° a mixture of 1-fluorovinyl 2,3,4-trifluoro-5-methylphenyl ketone (XVIII) (30%) and 2,5β,6,7,7aβ-pentafluoro-3aβ-methyl-3aβ,4,5,7a-tetrahydroinden-1-one (XXI) (22%) was formed from the possible internal Diels-Alder adducts (XVII) and (XX) respectively (Scheme 6). Pentafluorophenyl 2-methylbut-3-en-2-yl ether (XVI) decomposed under mild conditions (70°) to give pentafluorophenyl 3-methylbut-2-en-1-yl ether (XXII), pentafluorophenol and 2-methyl-1,3-butadiene possibly via an ion pair intermediate (Scheme 7).     

Synthesis,Characterization, and Cytotoxic Evaluation of New Triazole Derivatives of Osthol

Russian Journal of Organic Chemistry - Osthol [7-methoxy-8-(3-methylbut-2-en-1-yl)chromen-2-one] isolated from Prangos pabularia was used as a starting material for the synthesis of its various...     

Palladium(II)-catalyzed Amination of Isoprene with Aniline

The reaction of isoprene with aniline, catalyzed by the Pd(acac)₂-(RO)₃P-CF₃CO₂H system, 1 : 4 : 4 [R = Me, Et; acac = (CH₃CO)₂CH], in MeCN provides N-(3-methylbut-2-en-1-yl)aniline with a high selectivity (up to 84%) and a nearly quantitative yield (75%). At 1 : 4 : 20 and 1 : 4 : 40 molar component ratios in the catalytic system, up to 28–31% of N,N-(2,3-dimethylprop-2-en-1-yl)aniline is formed. Telomeric reaction products appear at 1 : 2 : 4 and 1 : 1 : 10 ratios.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 963–968.Original Russian Text Copyright © 2005 by Petrushkina, Mysova, Orlinkov.     

Approach to preparative synthesis of <Emphasis Type="Italic">ortho</Emphasis>-(1-methylbut-2-en-1-yl)anilines,precursors of new cytotoxic heterocycles

The reaction of aromatic Claisen rearrangement of N-(1-methylbut-2-en-1-yl)anilines in the presence of p-toluenesulfonic acid was investigated. N-Tosyl-2-(1-iodoethyl)-3-methylindoline derivatives were obtained; one of them exhibited a cytotoxic activity.     

Synthesis and molecular structure of new acyclic analogues of nucleotides with a 1,2-alkadienic skeleton

Reaction of 1-chloro-4-(diethoxyphosphonyl)alka-2,3-dienes 14,15 with purine and pyrimidine heterocyclic bases in the presence of cesium carbonate afforded new acyclic analogues of nucleotides containing a 1,2-alkadienic skeleton 18-23. Dealkylation of 18-23 furnished phosphonic acids 2a-f. In contrast, alkylation reaction with 1-chloro-4-(diethoxyphosphonyl)octa-2,3-diene 16 led to Z- and E-1,3-alkadienic phosphonates 25a,b and 26a,b. A similar reaction with 1-chloro-4-(diethoxyphosphonyl)-2-methylbuta-2,3-diene 17 led to the elimination of hydrochloride and formation of 4-(diethylphosphonyl)-2-methylbut-1-en-3-yne 24. Molecular structures of new acyclic nucleotides 18 and 2f are determined by X-ray crystallographic analysis.     

Glycosides of (+)-syringaresinol and 2-methylbut-3-en-2-yl β-D-glucopyranoside from the leaves ofNolina microcarpa

Two furofuranoid lignan glycosides, having the structures of (+)-syringaresinol 4′,4″-di-β-D-glucopyranoside (1) and (+)-syringaresinol 4′-β-D-glucopyranoside (2), and also 2-methylbut-3-en-2-yl β-D-glucopyranoside (3), have been isolated from an extract of the leaves ofNolina microcarpa (fam. Dracaenaceae).     

Reactions of 2,3-diferrocenylcyclopropenone with methyllithium and phenyllithium

Reactions of 2,3-diferrocenylcyclopropenone with methyllithium and phenyllithium afford products of the nucleophilic opening of the three-membered ring, viz., α,β-unsaturated ketones (cis-3,4-diferrocenylbut-3-en-2-one and cis-2,3-diferrocenyl-1-phenylprop-2-enone) and allylic alcohols (cis-3,4-diferrocenyl-2-methylbut-3-en-2-ol and cis-1,1-diphenyl-2,3-diferrocenylprop-2-en-1-ol). The insertion product of a methyl(diferrocenyl)vinylcarbenoid into a σ-bond of the starting compound, viz., 2,3,4-triferrocenyl-4-(1-ferrocenyl-2-oxopropyl)cyclobutenone, along with intramolecular ortho-alkylation products, viz., 2,3-diferrocenylindanone and 2,3-diferrocenyl-2-hydroxyindanone, were also isolated. X-ray diffraction data for triferrocenylcyclobutenone and 2,3-diferrocenyl-2-hydroxyindanone are presented.     

Synthesis and reactions of N-acetyl- and N-(2-chloroacetyl)-N-[(2E)-1-methylbut-2-en-1-yl]-2-iodoanilines

The reaction of N-(1-methylbut-2-en-1-yl)-2-iodaniline with Ac₂O or ClCH₂C(O)Cl results in a mixture of syn- and anti-atropisomers of N-acetyl- and N-chloroacetyl-N-(1-methylbut-2-en-1-yl)-2-iodaniline in a ratio of 1:1. Ozonolysis of the latter followed by reduction with dimethyl sulfide in CH₂Cl₂ gives rise to the atropisomers mixture of 2-[N-(chloroacetyl)-N-(2-iodophenyl)]aminopropanal in a ratio of 1:3. When heated in boiling benzene, the mixture of atropoisomeric aldehydes reacts with triphenylphosphine to afford a mixture of 2-[(N-acetyl)-N-(2-iodophenyl)]aminopropanal atropisomers in 1:3 ratio.     

Cyclization of ortho-(alk-2-enyl)anilines under the action of iodine

The reaction of ortho-(cyclohex-2-enyl)aniline with I₂ in nonpolar and polar solvents affords predominantly 1-iodohexahydrocarbazole and azatricyclotridecatriene, respectively. Under analogous conditions, 4-methyl-2-(1-methylbut-2-en-1-yl)aniline undergoes cyclization to form exclusively products with quinoline structures regardless of the solvent used.     

Photochemistry of Thiophen-2(5H)-ones

Mechanistic evidence for the light-induced ring opening of thiophen-2(5H)-ones 1 in alcohols affording α, β-unsaturated mercapto esters 2 is presented. Regio-and stereochemical aspects of the ring closure of alkenylthio (type 3 ) radicals 15 and 17 to S-heterocycles 16 and 18 , of 3-thiahex-5-enyl radicals 4 to (tetrahydrothien-3-yl)methyl radicals 6 and of (2,3-dihydrothien-3-yl)methyl radicals 30 (type 7, but-3-enyl radicals) to cyclopropane-methyl radicals 29 are discussed. Irradiation (λ 350 nm) of 1 in cyclohexane in the presence of 2,3-dimethylbut-2-ene affords [2 + 2] cycloadducts 14 albeit in very low yields.     

An elegant synthesis of some naturally occurring linear acetylchromenes: eupatoriochromene,methyleupatoriochromene (encecalin); evodionol and methylevodionol

An elegant synthesis of linear acetylchromenes, viz eupatoriochromene, methyleupatoriochromene (encecalin), evodionol and methlevodionol, has been achieved by blocking the reactive position position C-3 of the appropriate ketones with an iodo group, prenylation with 3-chloro-3-methylbut-1-yne and subsequent cyclisation. Regiospecific introduction of C-prenyl group in the less reactive C-5 has been achieved by the reaction of the appropriate 3-iodo ketones with 2-methylbut-3-en-2-ol. The 5-prenyl ketones are also essential intermediates for the synthesis of linear acetylchromenes.     

Reactions of allenylphosphonates with 1,2-diaminoethane

The reactions of dialkyl 3-methylbuta-1,2-dien-1-ylphosphonates with 1,2-diaminoethane lead to the formation of symmetrical N,N′-bis(1-dialkoxyphosphoryl-3-methylbut-1-en-2-yl)-1,2-diaminoethanes.     

An unexpected acid mediated rearrangement of monoethylene ketal of 2-methyl-2-(3-methylbut-2-en-1-yl)cyclohex-4-ene-1,3-diones to chromane

We herein report a serendipitously observed acid mediated rearrangement of monoethylene ketal of 2-methyl-2-(3-methylbut-2-en-1-yl)cyclohex-4-ene-1,3-diones to Dihydrobenzopyran and demonstrated the application of this methodology in the construction of core carbon scaffolds of dimethoxyajacareubin, cariphenone-A and crotamadine.