Synthesis 2012(3): 474-488  
DOI: 10.1055/s-0031-1289661
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Stereodivergent Synthesis of the C1-C9 Tetrahydropyran Subunit of Zincophorin and Isomers Thereof

François Godina,b, Ioannis Katsoulisa, Émilie Fiola-Massona, Sabrina Dhambria, Philippe Mochiriana,b, Yvan Guindon*a,b,c
a Institut de recherches cliniques de Montréal (IRCM), Bioorganic Chemistry Laboratory, 110 avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
Fax: +1(514)9875789; e-Mail: yvan.guindon@ircm.qc.ca;
b Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada
c Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, QC, H3A 2K6, Canada
Further Information

Publication History

Received 13 October 2011
Publication Date:
16 January 2012 (online)

Abstract

Zincophorin C1-C9 fragment and seven tetrahydropyran analogues were prepared diastereoselectively by sequential iodo­etherification and radical hydrogen-transfer reactions. Stereoselective formation of 3,7-trans or 3,7-cis rings was rationalized through minimization of allylic-1,3 strain in chair-like transition states. Subsequent hydrogen-transfer provided 7,8-anti or 7,8-syn isomers under acyclic stereocontrol or endocyclic control respectively. The latter approach relies on the formation of a [4.4.0] bicyclic complexes resulting from the chelation of the oxygen of the tetrahydropyran ring and the ester by a bidentate Lewis acid.

6

Numbering of atoms throughout article was attributed according to that of zincophorin 1.

26

Ligands on magnesium were not represented for simplicity.