Synthesis of optically active spiro-β-lactams by cycloadditions to α-alkylidene-β-lactams

New optically active α-methylene-β-lactam 18 and the α-ethylidene-β-lactams 11-E and 11-Z were synthesized and submitted to 1,3-dipolar cycloadditions with diazomethane, 4-methoxybenzonitrile oxide, and diphenylnitrone as well as to epoxidation by dimethyldioxirane. All cycloadditions proceed with c...

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Bibliographic Details
Published in:Tetrahedron 1998-06, Vol.54 (23), p.6369-6384
Main Authors: Anklam, Sven, Liebscher, Jürgen
Format: Article
Language:English
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Summary:New optically active α-methylene-β-lactam 18 and the α-ethylidene-β-lactams 11-E and 11-Z were synthesized and submitted to 1,3-dipolar cycloadditions with diazomethane, 4-methoxybenzonitrile oxide, and diphenylnitrone as well as to epoxidation by dimethyldioxirane. All cycloadditions proceed with complete regioselectivity giving products 20 – 25 in an anti-fashion with respect to the substituent at the C-4-position of the starting β-lactam in diastereomeric ratios of about 80:20. Pure optically active compounds could be obtained in almost all cases after chromatography. Unambiguous structure elucidation could be achieved by X-ray crystal analysis and NOE investigations. Graphic
ISSN:0040-4020
1464-5416
DOI:10.1016/S0040-4020(98)00296-8