Intramolecular palladium(II)-mediated alkoxy carbonylation as a route to functionalized tetrahydropyrans. Synthesis of the C9-C32 segment of phorboxazole A.
[reaction: see text] Hydroxy alkene 12, synthesized stereoselectively from 2-methyloxazole-4-carboxaldehyde, underwent intramolecular methoxy carbonylation in the presence of palladium(II) acetate to give 13 in which all five stereogenic centers around the tetrahydropyran correspond to those in ring C of phorboxazole A. Aldehyde 15, derived from 13, was linked to hydroxy alkene 23 via a Wittig coupling, and the composite 25 was subjected to a second palladium(II) acetate mediated methoxy carbonylation to yield 26, accompanied by acetoxy ester 27.
White
J D
JD
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA. james.white@orst.edu
Kranemann
C L
CL
Kuntiyong
P
P
D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D011714:Pyrans / Q000138:chemical synthesis / Q000737:chemistry*
D000970:Antineoplastic Agents; D006576:Heterocyclic Compounds, 4 or More Rings; D010080:Oxazoles; D011714:Pyrans; C408887:phorboxazole A; D010165:Palladium