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1, 3‐Cycloadditions to Highly Substituted, Strained Double Bonds: Spiro β‐lactams from α‐methylidene‐β‐lactams by reactions with diphenylnitrilimine, acetonitrile oxide, nitrones, and diazomethane
Author(s) -
Strauss Arthur,
Otto HansHartwig
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800606
Subject(s) - chemistry , diazomethane , regioselectivity , acetonitrile , lactam , cycloaddition , double bond , stereoselectivity , nitrone , stereochemistry , medicinal chemistry , organic chemistry , catalysis
Substituted dihydropyrazole‐spiro‐β‐lactams and isoxazolidine‐spiro‐β‐lactam derivatives are regio‐ and stereoselectively prepared by 1, 3‐cydoadditions between substituted α‐methylidene‐β‐lactams and diazomethane, nitrones, or the in ‐ situ ‐prepared dipoles ‘diphenylnitrilimine’ and acetonitrile oxide. These reactions represent examples for 1, 3‐cycloadditions to the highly substituted, strained double bonds of α‐methylidene‐β‐lactams, and they need special experimental conditions as all reaction products are relatively unstable. Especially in solution, the reverse reaction is highly favoured. Regioselectivity and stereoselectivity of the reactions are elucidated mainly by NMR techniques such as 2D‐INEPT, ATP, and NOE experiments.