Palladium(II)-catalyzed enantioselective synthesis of 2-vinyl oxygen heterocycles.
2-Vinylchromanes (1), 2-vinyl-1,4-benzodioxanes (2), and 2,3-dihydro-2-vinyl-2H-1,4-benzoxazines (3) can be prepared in high yields (90-98%) and excellent enantiomeric purities (87-98% ee) by [COP-OAc](2)-catalyzed cyclization of phenolic (E)-allylic trichloroacetimidate precursors. Deuterium-labeling and computational experiments are consistent with these cyclization reactions taking place by an anti-oxypalladation/syn-deoxypalladation mechanism. 2-Vinylchromanes can also be prepared in good yields and high enantiomeric purities from analogous (E)-allylic acetate precursors, which constitutes the first report that acetate is a competent leaving group in COP-catalyzed enantioselective S(N)2' substitution reactions.
Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, California 92697-2025, USA.
Jeffrey S
JS
Cannon
Angela C
AC
Olson
Larry E
LE
Overman
Nicole S
NS
Solomon
D000081:Acetamides; D048588:Benzoxazines / Q000138:chemical synthesis*; D002384:Catalysis; D062845:Chloroacetates; D002839:Chromans / Q000138:chemical synthesis*; D003198:Computer Simulation; D003500:Cyclization; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010880:Piperidines / Q000138:chemical synthesis*; D013194:Staining and Labeling; D013237:Stereoisomerism; D014238:Trichloroacetic Acid / Q000737:chemistry; D014753:Vinyl Compounds / Q000138:chemical synthesis*
D000081:Acetamides; D048588:Benzoxazines; D062845:Chloroacetates; D002839:Chromans; D010880:Piperidines; D014753:Vinyl Compounds; D010165:Palladium; D014238:Trichloroacetic Acid; D003903:Deuterium; C009528:trichloroacetamide; D010100:Oxygen