Sergei S. Novikov

Structural orientation in the diene condensation of trans-piperylene with some nitro dienophiles

1. A study was made of structural orientation in the diene condensation of trans-piperylene with the nitro dienophiles RCH=CHNO2, in which R=H, CH3, C6H5, CCl3, COOCH3. 2. In the condensation of trans-piperylene with nitroethylene(R=H)the only reaction product is the ortho isomer. 3. In the condensation of trans-piperylene with 1,2-disubstituted nitro dienophiles (R=CH3, C6H5, CCl3, COOCH3) in all cases two structurally isomeric adducts are formed with a great predominance of the ortho isomer.

Nitronium esters in reactions of 1,3-addition

1. The reaction of the O-methyl ester of phenylnitromethane with various Grignard reagents of general formula RMgX occurs unambiguously, independent of the nature of R, and leads to the formation of secondary hydroxylamines of general formula C6H5CH(R)N(R)OH. 2. The reaction of the O-methyl ester of phenylnitromethane with RMgX occurs by the scheme of 1,3-addition, in which connection the formed intermediate product reacts at a faster rate with the RMgX than does the starting O-methyl ester of phenylnitromethane.

On the mechanism of the reduction of carbonyl-contai ning compounds with a solution of diborane in tetrahydrofuran

1. A solution of diborane in tetrahydrofuran readily reduces chloral and chlorides of aliphatic carboxylic acids possessing electronegative substituents. 2. The introduction of substituents possessing a -I effect decelerates the reduction of complex esters and accelerates the reduction acid chlorides. The rate of reduction of aldehydes passes through a minimum as electronegative substituents accumulate. 3. The influence of halogen and alkyl substituents on the rate of reduction is proportional to their inductive effect. 4. The hypothesis was advanced that the complex of tetrahydrofuran with monoborane can directly carry out the reduction of carbonyl-containing compounds(ketones, aldehydes, acid chlorides). The probability of such reduction increases as electronegative substituents accumulate in the compound to be reduced. 5. The character of the reduction of complex esters with a solution of diborane in tetrahydrofuran differs from the reduction of other carbonyl-containing compounds.

Reduction of oximes with a solution of diborane in tetrahydrofuran

1. A solution of B6H6 in tetrahydrofuran reduces ketoximes to the corresponding alkylhydroxylamines. 2. The reduction of aldoximes by a solution of B6H6 in tetrahydrofuran is more complex and is not general in character.