Borane-mediated aldol cycloreduction of monoenone monoketones: diastereoselective formation of quaternary centers.
Exposure of monoenone monoketones to catecholborane in THF at ambient temperature results in tandem 1,4-reduction-aldol cyclization. For aromatic and heteroaromatic enones, six-membered cyclic aldol products are formed in excellent yield with high levels of syn diastereoselectivity. Five-membered ring formation proceeds less readily, but the yield of cyclized product is improved through introduction of Rh(I) salts.
Huddleston
Ryan R
RR
Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Cauble
David F
DF
Krische
Michael J
MJ
D001880:Boranes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006844:Hydrocarbons, Cyclic / Q000138:chemical synthesis*; D007659:Ketones / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012238:Rhodium / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
D001880:Boranes; D006844:Hydrocarbons, Cyclic; D007659:Ketones; D012238:Rhodium