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090			_aB-11109
245	1	0	_aSwitching from S- to R-Selectivity in the Candida antarctica Lipase B-Catalyzed Ring-Opening of ö-Methylated Lactones: Tuning Polymerizations by Ring Size
490	0		_vJ. Am. Chem. Soc., 129(23), p.7393-7398, 2007
520	3		_aNovozym 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
700	1	2	_aVan Buijtenen, J.
700	1	2	_aVan As, B.A.C.
700	1	2	_aVerbruggen, M.
700	1	2	_aRoumen, L.
700	1	2	_aVekemans, J.A.J.M.
700	1	2	_aPieterse, K.
700	1	2	_aHilbers, P.A.J.
700	1	2	_aHilbers, P.A.J.
700	1	2	_aPalmans, A.R.A.
700	1	2	_aMeijer, E.W.
856	4	0	_uhttps://drive.google.com/file/d/1N6g-zq8kOxoUUrb9TsyMUfrJMkqr3nZQ/view?usp=drivesdk _zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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