Catalytic Asymmetric Mannich-Ketalization Reaction: Highly Enantioselective Synthesis of Aminobenzopyrans
作者:Magnus Rueping、Ming-Yuan Lin
DOI:10.1002/chem.201000203
日期:2010.4.12
Domino catalysis: We have developed the first enantioselective domino Mannich–ketalization reaction of o‐hydroxy benzaldimines with electron‐rich alkenes (see scheme). The new reaction sequence provides an easy and direct access to optically pure 4‐aminobenzopyrans in good yields and with excellent enantiomeric ratios (up to e.r. 98:2).
NaHSO<sub>4</sub>–SiO<sub>2</sub>-catalyzed aza-Diels–Alder reaction of <i>o</i>-hydroxybenzaldimines with 2,3-dihydrofuran: Diastereoselective synthesis of furanobenzopyrans
作者:Pfanelo Mulokwe、Mokgethwa B. Marakalala、Tommy F. Mabasa、Henok H. Kinfe
DOI:10.1080/00397911.2017.1377257
日期:2017.12.17
ABSTRACT NaHSO4 supported on silicagel catalyzes the aza-Diels–Alder reaction of o-hydroxybenzaldimines with 2,3-dihydrofuran to provide furanobenzopyrans in reasonable yields and diastereoselectivity. The catalyst is recyclable and reusable up to two times without a significant loss of activity. GRAPHICAL ABSTRACT