TRANSFORMATIONS OF PYRIDINE AND DEUTEROPYRIDINE UNDER THE ACTION OF TRIMETHALLYLBORANE AND ALCOHOLS - SYNTHESIS OF TRANS-2,6-DIMETHALLYL-1,2,3,6-TETRAHYDROPYRIDINES AND CIS-2,6-DIMETHALLYL-1,2,3,6-TETRAHYDROPYRIDINES AND THEIR N-DERIVATIVES

Reductive trans-2,6-dimethallylation of pyridine and deuteropyridine w ith trimethallylborane in the presence of alcohols proceeds at room te mperature, i.e., under substantially milder conditions than the analog ous reaction with the participation of triallylborane. trans-2,6-Di(2- methylallyl)-1 ,2,3,6-tetrahydropyridine (3) was obtained in a yield o f 87%. When heated with trimethallylborane (130-135 degrees C, 2.5 h), compound 3 underwent isomerization to s-2,6-di(2-methylallyl)-1,2,3,6 -tetrahydropyridine (4). Hydrogenation of trans-(3) and cis-isomers (4 ) yielded trans-and cis-2,6-diisobutylpiperidines, respectively. The h eterocycles obtained were N-functionalized by reactions with Mel, PhCH 2Cl, ethylene oxide, and perfluoropropyloxirane. The stereochemistry o f the cis-and trans-isomers (3 and 4) was established based on the NMR spectra of their N,N-dimethyl salts and the products of the reaction with ethylene oxide. trans-2,6-Dimethallyl-2,3,4,5,6-pentadeutero,2,3, 6-tetrahydropyridine and a number of its derivatives were prepared fr om the complex of trimethallylborane with C5D5N A probable mechanism o f the reductive trans-2,6-diallylation of pyridines with allylboranes in the presence of alcohols is discussed.