Lipase-catalyzed transesterification of meso-cyclopentane diols

Synthesis of Novel Spinosyn A Analogues by Pd‐Mediated Transformations

“…An alternative second route allowed the enantioselective synthesis of both enantiomers of the lactone 23 starting from meso compounds 24 and 25, respectively (Scheme 5). Thus, enzymatic acetylation of diol 25 with pancreatin and vinyl acetate afforded (À)-26 [15] in 72 % yield and 99 % ee, and enzymatic deacetylation of 24 with novozym 435 gave (+)-26 [16] in 96 % yield with an identical ee of 99 %. These compounds can be transformed in four steps into both enantiopure lactones.…”

Specificity of Candida antarctica lipase B (SP 435) in the presence of lipase A in a double enantioselective transesterification

“…It is therefore not surprising that the transesterification of the meso-diol 5 with either vinyl or isopropenyl acetate gives for both lipases SP 382 (lipase A + B) (F. Theil et al, 1991) and SP 435 (lipase B) (Johnson and Bis, 1992) the same results according to yield and enantiomeric excess of the resulting chiral monoacetate 6 (Scheme 2). It can be concluded that the selectivity of these transesterifications is determined by the component B of the C. antarctica lipase while the activity of the component A is completely suppressed under the reaction conditions.…”

“…This preparation is found to be very suitable as catalyst in organic synthesis (Bjiirkling et al, 1990, Theil et al, 1991. The two lipase components from C. antarctica, A and B, have both been isolated and purified.…”

“…The lipases are from NOVO Nordisk AfS, Denmark. The meso-dial 1 was prepared as reported (Theil et al, 1991). 2,2,2-trifluoroethyl2-chloropropanoate (rat-2) was prepared in an usual manner from 2-chloropropanoyl chloride and 2,2,2&fluoroethanol in triethylamine in the presence of a catalytic amount of 4-dimethylaminopyridine.…”

Multiple Palladium‐Catalyzed Reactions for the Synthesis of Analogues of the Highly Potent Insecticide Spinosyn A

“…[9] The intermolecular Heck reaction of 5 and 7 with Pd(OAc) 2 in DMF provided the desired coupled product 8 diastereomerically pure in 51 % yield. [10] A regioisomer of 5 with a coupling at the 3'-position and the corresponding compounds with an E-configured styrene double bond were isolated as further products.…”