TY  - BOOK
AU  - Van Buijtenen,J.
AU  - Van As,B.A.C.
AU  - Verbruggen,M.
AU  - Roumen,L.
AU  - Vekemans,J.A.J.M.
AU  - Pieterse,K.
AU  - Hilbers,P.A.J.
AU  - Hilbers,P.A.J.
AU  - Palmans,A.R.A.
AU  - Meijer,E.W.
TI  - Switching from S- to R-Selectivity in the Candida antarctica Lipase B-Catalyzed Ring-Opening of ö-Methylated Lactones: Tuning Polymerizations by Ring Size
N2  - Novozym 435-catalyzed ring-opening of a range of ö-methylated lactones demonstrates fascinating differences in rate of reaction and enantioselectivity. A switch from S- to R-selectivity was observed upon going from small (ring sizes e7)to large lactones (ring sizes g8). This was attributed to the transition from a cisoid to a transoid conformational preference of the ester bond on going from small to large lactones. The S-selectivity of the ring-opening of the small, cisoid lactones was low to moderate, while the R-selectivity of the ring-opening of the large transoid lactones was surprisingly high. The S-selectivity of the ring-opening of the small, cisoid lactones combined with the established R-selectivity of the transesterification of (aliphatic)secondary alcohols prevented polymerization from taking place. Ringopening of the large, transoid lactones wasR-selective with high enantioselectivity. As a result, these lactones could be polymerized, without exception, by straightforward kinetic resolution polymerization, yielding the enantiopure R-polyester with excellent enantiomeric excess (>99
UR  - https://drive.google.com/file/d/1N6g-zq8kOxoUUrb9TsyMUfrJMkqr3nZQ/view?usp=drivesdk
ER  -