Efficient preparation of highly optically active (S)-(-)-2,3-allenols and (R)-(+)-2,3-allenyl acetates by a clean novozym-435-catalyzed enzymatic separation of racemic 2,3-allenols.
Novozym-435 has been found to be an effective biocatalyst for the kinetic resolution of a series of racemic 2,3-allenols, affording highly optically active (S)-(-)-2,3-allenols and (R)-(+)-2,3-allenyl acetates in high yields and with excellent ee values. The reaction of 3-(n-butyl)-3,4-pentadien-2-ol (1 a) was successfully performed on a 10 g scale to afford the corresponding (S)-(-)-2,3-allenol (1 a) and (R)-(+)-2,3-allenyl acetate (2 a) in synthetically useful amounts and with high ee values. The advantages of this reaction are the ready availability of the starting materials, high stereoselectivities for both (-)-2,3-allenols and (+)-2,3-allenyl acetates, the use of a relatively high substrate concentration, and a lower catalyst loading. The resulting (S)-(-)-2,3-allenol 1 a can be converted into the corresponding chiral 2,5-dihydrofuran and the vinylic epoxide.
Xu
Daiwang
D
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, P.R. China.
Li
Zuyi
Z
Ma
Shengming
S
D000085:Acetates / Q000737:chemistry / Q000302:isolation & purification; D000438:Alcohols / Q000737:chemistry / Q000302:isolation & purification*; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry; D009904:Optical Rotation; D013237:Stereoisomerism
D000085:Acetates; D000438:Alcohols; D004798:Enzymes; D008049:Lipase