ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19970800606