Automatic assembly of framework structures. 1. Synthesis, stereochemistry, and cyclization of derivatives of ?,??-dihydroxy-?,??-dimethyl- and ?-methyl-??-ethylglutaric acids

Abstract

1. The principle of the stereocontrolled assembly of framework structures was confirmed for the case of the synthesis of bicyclic compounds with high yields under mild conditions from derivatives of d,l-α,α′-dihydroxy-α,α′-dimethyl- and threo-α,α′-dihydroxy-α-methyl-α′-ethylglutaric acids. 2. The conformation of the five-membered heterocycles in the derivatives of d,l- and meso-α,α′-dihydroxy-α,α′-dimethylglutaric acid and threo- and erythro-α,α′-dihydroxy-α-methyl-α′-ethylglutaric acids was studied. For the former it was shown that the functional groups have the a,a orientation, which favors secondary cyclization. On this basis the general principle of conformational control during the assembly of bicyclic systems from the monocyclic precursors was formulated. In the derivatives of the meso and erythro series the conformation of the ring changes with increase in the size of the substituent from a-CN to e-COOH and e-COOR. 3. It was shown that the products previously described as biscyanohydrins of acetylacetone and propionylacetone have the iminolactone structure.