A facile synthesis of 3-cyclopropyl- and 5-cyclopropyl-isoxazoles

The regioselective synthesis of isomeric isoxazoles 3-(2-arylcyclopropyl)-5-methylthio- and 5-(2-arylcyclopropyl)- 3-methylthio-isoxazoles is described

Reaction of lithioamino anions with α-oxoketene dithioketals: an improved and a new general method for the synthesis of α-oxoketene S, N- and N, N-ketals

A new method has been developed for the preparation of α -oxoketene S,N- (A) and N,N-(B) ketals starting from α -oxoketene dithioketals by employing mild conditions. Thus, lithioamino anions 2a-c, 4 and 6 are treated with α -oxoketene dithioketals 1 to afford the corresponding S,N-ketals 3a-j, 5a-j, 7a-e and N,N-ketals 8a,b in good yields. The scope and steric orientations of the reaction have been investigated

Reaction of β-oxodithioesters with propargylamine: a facile entry to novel 2-(acylalkylidene)-5-(methylene)thiazolidines

Reaction of β-oxodithioesters derived from acyclic and cyclic ketones with propargylamine affords novel 2-(acylalkylidene)-5-(methylene)-thiazolidines in high yields by intramolecular nucleophilic attack of thiocarbonyl sulfur on the triple bond of the β-oxo-N-propargylthioamide intermediates

Trimethylsilyl chloride assisted conjugate addition-elimination of organocopper reagents to 2-bis(methylthio)nitroethylene: an efficient and highly stereoselective synthesis of 2-methylthio-2-alkyl/aryl-1-nitroethylenes and their application for synthesis of nitroheterocycles

An efficient method for the synthesis of novel 2-methylthio-2-alkyl/aryl-1-nitroethylenes 2 has been developed via conjugate addition-elimination of organocopper reagents to nitroketene dithioacetal 1 in the presence of TMSCl. The product nitroethylenes 2 have been further utilized for the synthesis of substituted 3-nitro-2-alkyl/arylpyrroles 5 by their reaction with aminoacetaldehyde dimethylacetal followed by acid catalyzed cyclization in ethereal HCl. The reaction of 2 with propargyl alcohol has also been investigated

Anionic [4 + 2] cycloaddition reactions of dihydropyrazolin-5-one dienolate with dienophiles: a novel approach for substituted and fused indazolones

Dihydropyrazolin-5-one dienolate 2 generated by deprotonation of 2,3-dimethyl-4-formyl-1-phenylpyrazolin-5-one (4-formylantipyrine) is shown to be an efficient anionic pyrazolone α -oxy-o-quinodimethane analog, which undergoes facile cycloaddition with a variety of dienophiles to give substituted indazolones in good yields after dehydration-dehydrogenation of cycloadducts

Preparation of lithium 5-lithiomethy-3-methylpyrazole-1-carboxylate and its reaction with α-oxoketene dithioacetals: a new general method for substituted and annelated pyrazolo[1,5-a]pyridines

5-Methylpyrazole derivative 1 is metallated at the C-5 methyl carbon atom to form lithium 5-lithiomethyl-3-methylpyrazole-1-carboxylate 3 which on reaction with α-oxoketene dithioacetals 4a-d, 12a-c and 15a-b yields substituted and annelated pyrazolo[1,5-a]pyridines 7a-d, 13a-c and 16a-b

Direct synthesis of 2-(cycloalkylamino)-3,4-substituted thiophenes via selective deprotonation-cyclization of aroyl ketene N,S-acetals

Acyclic and cyclic aroyl ketene N,S-acetals undergo regioselective deprotonation-cyclization via dipole stabilized carbanion in the presence of LDA/THF to afford the corresponding 2-(cycloalkylamino)-4-aryl or 3,4-annelated thiophenes in moderate to good yields

Heteroaromatic annulation studies on 2-[bis(methylthio)methylene]- 1-methyl-3-oxoindole: synthesis of novel heterocyclo[b] fused indoles

Heteroannulation of 2-[Bis(methylthio)methylene]-1-methyl-3-oxoindole with β- substituted β-lithioaminoacrylonitrile, malononitrile and guanidine has been reported to yield novel substituted pyrido[3,2-b]indoles and pyrimido[5,4-b]indole derivatives in varying yields

Synthesis of novel 3-cyano-4-methylthio-6-(arylcyclopropyl)-3-(1H)-pyridones and 5(3)-methylthio-3(5)-(arylcyclopro-pyl)pyrazoles

1056-105

Lewis acid-induced rearrangment of α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols: unexpected formation of a novel bicyclo[3.2.1]octadiene framework

The α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols 9a-c undergo a simple but unexpected skeletal rearrangement in the presence of stannic chloride in nitromethane to afford bicyclo[3.2.1]octadiene derivatives 10a-c exclusively in good yields. The structure of 10a was conclusively elucidated by X-ray diffraction studies. A possible mechanism governing the formation of 10 is proposed