Propane-1,3-diols enantioselective

Molinari, F., Gandolfi, R., Villa, R., Urban, E. and Kiener, A. (2003) Enantioselective oxidation of prochiral 2-methyl-l, 3-propan diol by Acetobacter pasteurianus. Tetrahedron Asymmetry,... 

A series of alkyl, alkoxy or acylamino 1,3-proanediol derivatives substituted in 2-position have been subjected to lipase-catalyzed acylation, and the monoacetates (1-12, 19, 20, 23-38, 40-42) were obtained with moderate to high enantiomeric excess (Table 11.1-17). For the monoacetates 1-12, reactions with and in ethyl acetate are usually slower than those with and in vinyl acetate. As in the hydrolysis of the corresponding diacetates, much higher selectivities were recorded with the yet unidentified carboxyl esterase from crude pig pancreas lipase. An excellent lipase for the enantioselective acylation of 3-benzyloxy-l,3-propane diol is Pseudomonas fluor-escens lipase, which gives high selectivity with vinyl acetate, isopropenyl acetate and ethyl acetate. By carrying the acylation further, to a certain extent to the diacetate, the enantiomerically pure monoacetate should be obtainable. 

Kollar et al. prepared diastereomers of diphosphites which were synthesized by combining different modifications in the bridge and the phosphorus substituents [27, 28] 1. These ligands lead to active rhodium systems, and are considerably affected by chiral cooperativity. Some of these diastereomers prepared from (2S,4S) 2,4-pentenediol and (1 S,3S) diphenyl propane 1,3-diol form rhodium complexes in which the ligand is coordinated in an eight-membered ring, 14, 15, but the enantioselectivity obtained in the experiments described are no higher than 24% [27],... 

The fragrance industry has taken advantage of the use of enantioselective desymmetrization processes for instance, the selective acylation of 2-hydroxymethyl-3-(4-isopropylphenyl)-l-propanol with vinyl butanoate led to the corresponding enantiopure monoester in 97% yield (Figure 9.13), which is a precursor of cyclamen aldehyde, an important component for obtaining special blossom notes in perfume compositions [151]. In a 5g scale the successful desymmetrization of 2-(2, 2 -dimethoxyethyl) propane-l,3-diol has been reported using PFL and 1.3 equivalents of VinOAc in... 

Hayashi and co-workers applied the asymmetric direct aldol reaction for the synthesis of chiral building block 75 for (+)-cytotrienin A 76," which is a microbial antitumor secondary metabolite. The diol 75 was synthesized with high enantioselectivity by means of the organo-catalytic aldol reaction of furfural 55 and propanal 39 in the presence of a catalytic amount of 4-acyloxy proline 74 (Scheme 27.13). The original procedure, i.e., with proline as a catalyst, was not effective for large-scale synthesis of 75 because of low yield and low diastereoselec-tivity. Total synthesis of (+)-cytotrienin A 76 was achieved in another 32 steps from diol 75. 

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