Stereocontrolled synthesis of N-vinyl-, N-(1'-propenyl)-, and N-unsubstituted-.beta.-lactams from 2-aza-1,3-butadienes via the Staudinger reaction
摘要:
2-Aza-1,3-butadienes 2 and 5 were synthesized in good yields and on a large scale. Reaction of 2 and 5 with acid chlorides in the presence of triethylamine (Staudinger reaction) resulted in the high-yielding formation of N-vinyl- and N-(1'-propenyl)-beta-lactams. Excellent cis-stereoselectivity was observed in the reaction of 2-aza-1,3-butadienes 2 and 5 with Bose-Evans ketenes and Sheehan ketenes, whereas reaction with a Moore ketene gave, as expected, a trans beta-lactam. N-Formyl, N-vinyl, and N-(1'-propenyl) groups at the beta-lactam nitrogen could be cleaved oxidatively in one step and in good yields by treatment with potassium permanganate. It was also found that the N-vinyl group can be removed successfully under hydrolytic, conditions to yield N-unsubstituted-beta-lactams.
Diastereospecific synthesis of novel tetracyclic β-lactams via 6-exo-trig radical cyclization
作者:Sudhir N. Joshi、V.G. Puranik、A.R.A.S. Deshmukh、B.M. Bhawal
DOI:10.1016/s0957-4166(01)00550-x
日期:2001.12
An efficient and diastereospecific synthesis of a tetracyclic, 3.6.6.4 ring system fused to a β-lactam has been achieved in high yield via 6-exo-trig radicalcyclization.