Premium
Tandem Inter [4+2]/Intra [3+2] Cycloadditions of Nitroalkenes. Application to the Synthesis of Aminocarbasugars
Author(s) -
Denmark Scott E.,
Juhl Martin
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200211)85:11<3712::aid-hlca3712>3.0.co;2-5
Subject(s) - chemistry , nitroalkene , stereoselectivity , moiety , cycloaddition , tandem , stereochemistry , nitroso , combinatorial chemistry , yield (engineering) , sequence (biology) , organic chemistry , enantioselective synthesis , catalysis , biochemistry , materials science , metallurgy , composite material
The tandem inter [4+2]/intra [3+2] cycloaddition of nitroalkenes in the bridged mode was applied to the stereoselective synthesis of β ‐ D ‐4‐amino‐2,4‐dideoxycarbagulose, a representative aminocarbasugar. The synthesis required only five steps from known materials and delivered the protected aminocarbasugar (−)‐ 20 in excellent yield (see Scheme 9 ). The success of the synthetic sequence relies on 1 ) the ability to incorporate O‐substituents at the nitroalkene moiety, 2 ) the identification of a suitably modified chiral dienophile, and in particular 3 ) the development of specific experimental conditions and protocols that allow for the formation and isolation of the highly sensitive nitroso acetals. The reduction of the C(1) carbonyl group of (+)‐ 19 gave unexpected stereoselectivity, which could be rationalized by a conformational inversion of the substrate (see Scheme 11 ).