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.
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.
Wu
Yikang
Y
State Key Laboratory of Bio-organic & Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China.
Shen
Xin
X
Tang
Chao-Jun
CJ
Chen
Zhi-Long
ZL
Hu
Qi
Q
Shi
Wei
W
D007783:Lactones / Q000138:chemical synthesis*; D029595:Orchidaceae / Q000737:chemistry; D010476:Perfume / Q000138:chemical synthesis*; D013237:Stereoisomerism
D007783:Lactones; D010476:Perfume