Use of some aryl and heteroaryl nitrilimines and nitrones in the synthesis of spiroheterocycles

摘要

1,3-Dipolar cycloadditions of C-(5-nitro-2-furyl)-N-methyl nitrilimine (2a), C-(5-nitro-2-furyl)-N-phenyl nitrilimine (2b), C-4-nitrophenyl-N-methyl nitrilimine (2c) and C,N-diphenyl nitrilimine (2d) with 1-R-substituted 3,3-methylene-5,5-dimethylpyrrolidin-2-ones (1a-d) where R is H, acetyl, 1,1-dimethylethoxycarbonyl and 1-methylethenyl proceed with complete regioselectivity in good yields to afford 1,3,7-trisubstituted-6-oxo-8,8-dimethyl-1,2,7-triazaspiro[4,4]non-2-enes (5a-g) exclusively. Cycloaddition of C-(5-nitro2-furyl)-N-phenylnitrone (3b) to the exocyclic double bond of the dipolarophile la proceeds to 2-phenyl-3-(5-nitro-2-furyl)-6-oxo-8,8-dimethyl-1-oxa-2,7-diazaspiro[4,4]nonane (7) with complete regio- and stereoselectivity.