Synthesis of Antitumor Lycorines by Intramolecular Diels−Alder Reaction
摘要:
Pharmacologically interesting lycorines were obtained by a short, efficient method based on an intramolecular Diels-Alder reaction between an alpha-pyrone and an alkyne, followed by loss of CO2 in a retro Diels-Alder reaction. The cyclization precursors (pyrones 9) were obtained in good yields in two or three steps from the corresponding homophthalic acid or anhydride.
Diastereoselective Base-Catalyzed Formal [4 + 2] Cycloadditions of <i>N</i>-Sulfonyl Imines and Cyclic Anhydrides
作者:Stephen W. Laws、Lucas C. Moore、Michael J. Di Maso、Q. Nhu N. Nguyen、Dean J. Tantillo、Jared T. Shaw
DOI:10.1021/acs.orglett.7b00468
日期:2017.5.19
A diastereoselective base-catalyzed Mannich reaction of cyclic, enolizable anhydrides and N-sulfonyl imines for the synthesis of δ-lactams is reported. This anhydride Mannich reaction tolerates imines derived from aryl and enolizable aldehydes. A base-catalyzed product epimerization pathway ensures high anti diastereoselectivity in aryl and achiral enolizable imines.
The interaction between 1,3-isochromanediones(homophthalic anhydrides) 1 and acyclic azomethines of types 2 and 3 and the cyclic 6,7-dimethoxy-3,4-dihydroisoquinoline 4 is investigated. The former lead in high yields to the (±)-trans-3-aryl-4-carboxy-3,4-dihydro-1(2H)-isoquinolinones 5, while the latter gives the (±)-cis-13-carboxy-8-oxoberbines 7. The relative configurations of compounds 5–8 as well