A cascade sequence between cyclic hemiacetals and tryptamines was developed, which provided efficient access to highly substituted diazaindeno[2,1-α]phenanthrenes in moderate to good yields with high diastereoselectivities and good to excellent enantioselectivities. Hemiacetals were prepared by asymmetric organocatalyzed conjugate addition of cyclic 1,3-diketones to α,β-unsaturated aldehydes. Hemiacetals
General and Efficient Organocatalytic Synthesis of Indoloquinolizidines, Pyridoquinazolines and Quinazolinones through a One-Pot Domino Michael Addition-Cyclization- Pictet-Spengler or 1,2-Amine Addition Reaction
作者:Magnus Rueping、Chandra M. R. Volla、Michael Bolte、Gerhard Raabe
DOI:10.1002/adsc.201100258
日期:2011.10
organocatalyzed reaction sequence involving a Michaeladdition of various 1,3-dicarbonyl compounds to α,β-unsaturated aldehydes with subsequent diastereoselective Pictet–Spengler cyclization has been developed. The substrate scope was found to be general and optically active indoloquinolizidines were isolated as single diastereomers in high yields with high to excellent enantioselectivites. In addition to tryptamine