Desymmetrization lipase-mediated

Cycloheptatriene has been converted into L-glucose via Pseudomonas cepacia lipase-mediated desymmetrization of a meso-3-O-pmtected cyclohept-6-ene-l,3,5-triol using isopropenyl acetate as the solvent [499,500,501]. 

Malonic esters are desymmetrized by exchange of one of the ester groups, and chiral carboxylic esters are obtained from lipase-mediated alcoholysis of mixed carboxylic carbonic anhydrides. ... 

Kielbasinski P, Albrycht M, Zurawinski R, Mikolajczyk M (2006) Lipase-mediated kinetic resolution of racemic and desymmetrization of prochiral organophosphorus P-boranes. J Mol Catal B 39 45 9... 

High yields and >99% ee were achieved in the lipase-mediated desymmetrization of 2,3-0-cyclohexylidene-erythritol 34, as shown in Scheme 3. The acetonide 35 was similarly asymmetrically acetylated to give the monoacetate 36, which was employed in a synthesis of (+)-em/o-brevicomin (see Chapter 24). The enzymatic kinetic resolution of racemic synthetic glycals is referred to in Chapter 13. 

The first enzymatic desymmetrizations of prochiral phosphine oxides was recently reported by Kielbasinski et al.88 Thus, the prochiral bis(methoxycarbonylmethyl)-phenylphosphine oxide 93 was subjected to the PLE-mediated hydrolysis in buffer affording the chiral monoacetate (RJ-94 in 72% ee and 92% chemical yield. In turn, the prochiral bis(hydroxymethyl)phenylphosphine oxide 95 was desymmetrized using either lipase-catalyzed acetylation of 95 with vinyl acetate as acyl donor in organic solvent or hydrolysis of 97 in phosphate buffer and solvent affording the chiral monoacetate 96 with up to 79% ee and 76% chemical yield. 

A total synthesis of the dipyrrolidine alkaloid (—)-trans-dendrochrysine (22), isolated from the orchid endemic Dendrohium chrysanthum, was achieved by Blechert and coworkers utilizing RRM [21]. The asymmetric synthesis commenced with preparation of diolefin 20 from commercially available tropone (19, Scheme 2.6) in 11 steps involving a solid-phase supported Candida antarctica lipase B (Cal-B)-mediated desymmetrization. 

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