title: Synthesis of natural fragrant molecules cis-3-methyl-4-decanolide and aerangis lactone. General enantioselective routes to beta,gamma-cis-disubstituted gamma-lactones and gamma,delta-cis-disubstituted delta-lactones.
abstract: General enantioselective routes to 3,4-cis-dialkyl substituted gamma-lactones and 4,5-cis-dialkyl substituted delta-lactones using TiCl(4)-mediated Evans asymmetric aldolization as the key step are reported. The syntheses are exemplified with two natural fragrant molecules, cis-3-methyl-4-decanolide (1) and aerangis lactone (2). The (R,R) steroegenic centers were established using (S)-phenylalanine-derived 2-oxazolidinone or thiazolidinethione as chiral auxiliary, whereas the (S,S) ones were constructed with auxiliary prepared from (R)-phenylglycine. NaBH(4)/CaCl(2)/THF in the presence of a small amount of EtOH was introduced as a new effective method for reductive cleavage of chiral oxazolidinone auxiliaries. Previously unknown, tricky concentration effects were observed during the monotosylation of diol 7 and BOM protection of Evans aldol 23.
authors.affiliation: State Key Laboratory of Bio-organic & Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China.
authors.forename: Yikang
authors.initials: Y
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Shen
authors.forename: Chao-Jun
authors.initials: CJ
authors.lastname: Tang
authors.forename: Zhi-Long
authors.initials: ZL
authors.lastname: Chen
authors.forename: Qi
authors.initials: Q
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
mesh_terms: D007783:Lactones / Q000138:chemical synthesis*; D029595:Orchidaceae / Q000737:chemistry; D010476:Perfume / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D007783:Lactones; D010476:Perfume