Formal [4+2]-annulation of chiral crotylsilanes: synthesis of the C19-C28 fragment of phorboxazoles.
A stereoselective synthesis of the C19-C28 fragment of phoborxazole A and B is described. The key step is an enantioselective [4 + 2]-annulation of a crotylsilane 10 with a propargylic aldehyde 11 affording a functionalized dihydropyran 12. A solvent-dependent stereoselective epoxidation of dihydropyrans is also documented.
Huang
H
H
Department of Chemistry, Metcalf Center for Science and Engineering, 590 Commonwealth Avenue, Boston University, Boston, Massachusetts 02215, USA.
Panek
J S
JS
D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis*; D002384:Catalysis; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D010080:Oxazoles / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D011161:Porifera / Q000737:chemistry*; D013237:Stereoisomerism
D000970:Antineoplastic Agents; D006576:Heterocyclic Compounds, 4 or More Rings; D007202:Indicators and Reagents; D010080:Oxazoles; C408887:phorboxazole A