anti-Diastereo- and enantioselective carbonyl (hydroxymethyl)allylation from the alcohol or aldehyde oxidation level: allyl carbonates as allylmetal surrogates.
Enantioselective transfer hydrogenation of carbonate 1a in the presence of aromatic, allylic, or aliphatic alcohols 2a-2i employing a cyclometalated iridium C,O-benzoate derived from allyl acetate, 4-cyano-3-nitrobenzoic acid and (S)-SEGPHOS delivers products of (hydroxymethyl)allylation 4a-4i in good isolated yields (60-74%), good anti-diastereoselectivities (5:1-10:1 dr) and exceptional levels of enantiocontrol (93-99% ee). Under identical reaction conditions, but in the presence of isopropanol, aldehydes 3a-3i are converted to an equivalent set of adducts 4a-4i in good isolated yields (58-74%), good anti-diastereoselectivities (4:1-14:1 dr), and exceptional levels of enantiocontrol (95-99% ee). Thus, identical sets of adducts 4a-4i are produced with equal facility from the alcohol or aldehyde oxidation level. These studies represent the first general method for enantioselective carbonyl (hydroxymethyl)allylation, a process that has no highly stereoselective counterpart in conventional allylmetal chemistry.
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Yong Jian
YJ
Zhang
Jin Haek
JH
Yang
Sang Hoon
SH
Kim
Michael J
MJ
Krische
D000438:Alcohols / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D000498:Allyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D000438:Alcohols; D000447:Aldehydes; D000498:Allyl Compounds; D002254:Carbonates; D009942:Organometallic Compounds; D007495:Iridium