Hybrid‐Type Squaramide‐Fused Amino Alcohol Organocatalysts for Enantioselective Diels–Alder Reactions of 3‐Hydroxy‐2‐Pyridones with Maleimides. Issue 31 (23rd August 2017)

• Record Type: Journal Article
• Authors: Chennapuram, Madhu; Subba Reddy, U. V.; Seki, Chigusa; Okuyama, Yuko; Kwon, Eunsang; Uwai, Koji; Tokiwa, Michio; Takeshita, Mitsuhiro; Nakano, Hiroto
• Is Part Of: European journal of organic chemistry. Issue 31(2017)
• Page Start: 4633
• Page End: 4641
• Publication Date: 2017-08-23
• Subjects: Amino alcohols -- Nitrogen heterocycles -- Diels–Alder -- Organocatalysis -- Enantioselectivity; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201700830
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : The hybrid‐type squaramide‐fused amino alcohol (SFAA) containing both a Brønsted basic site and a hydrogen‐bonding site in the molecule showed high catalytic activity as an organocatalyst in the enantioselective Diels–Alder (DA) reactions of 3‐hydroxy‐2‐pyridones with maleimides to afford chiral endo ‐4‐hydroxy‐2‐azabicyclo[2.2.2]octanes (4‐hydroxyisoquinuclidines) with excellent chemical yields and enantioselectivities (up to 95 % yield and 98 % ee ). In particular, the use of 4‐brominated 2‐pyridones afforded the corresponding chiral 4‐hydroxyisoquinuclidines with both excellent chemical yields and enantioselectivities (95 %, 98 % ee ) with an opposite absolute stereochemistry in comparison with the chiral endo ‐DA adducts obtained from the reactions performed with common 3‐hydroxy‐2‐pyridones. The DA adducts obtained could be used as synthetic precursors for several natural products that have a broad spectrum of fascinating biologically activities. Abstract : A new hybrid‐type squaramide‐fused amino alcohol organocatalyst containing both a Brønsted‐basic site and a hydrogen‐bonding site showed high catalytic activity in the enantioselective Diels–Alder reactions of 3‐hydroxy‐2‐pyridones with maleimides to afford the chiral 4‐hydroxyisoquinuclidines with high regio‐ and stereoselectivity.