Science of Synthesis

Oriyama, T., Science of Synthesis: Stereoselective Synthesis, (2011) 3, 838.

Many effective methods for the kinetic resolution of racemic secondary alcohols with acid anhydrides and acid halides have been developed to give the corresponding optically active esters. However, the kinetic resolution using free carboxylic acids as acyl donors has great synthetic potential as numerous carboxylic acids, including aliphatic and aromatic types, are commercially available. For example, the kinetic resolution of a variety of racemic secondary benzylic alcohols to give optically active esters is possible using free carboxylic acids, benzoic anhydride, and a tetramisole-derived catalyst, which represents the first example of asymmetric acylation of racemic secondary alcohols with an achiral carboxylic acid.[‌38‌] The tetramisole derivative (+)-benzotetramisole [(+)-‌31‌; (+)-BTM] is prepared as outlined in ‌Scheme 12‌.[‌39‌] In this procedure 2-chlorobenzo[d]thiazole (‌28‌) undergoes substitution with (R)-2-amino-2-phenylethanol (‌29‌) to give (R)-2-(benzo[d]thiazol-2-ylamino)-2-phenylethanol (‌30‌). This is followed by mesylation of the primary alcohol group and ring closure to give the catalyst.

‌Meeeee 88‌ Meeeeeeee ee (+)-Meeeeeeeeeeeeeee[‌88‌]

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‌Meeeee 88‌ Meeeeee Meeeeeeeee ee Meee Meeee Meeeeeeee eeee Meeeeeeeee Meeee[‌88‌]

‌Meeeeeeeeee 88‌

Mee eeeeeee eeeeeeee eeeeeee ee eeeeeeeeeee ee ‌Meeeee 88‌. Me eee eeeee eeeee, eeeee eeeeeeeee ‌88‌ ee eeeeee ee e eee eeeeeeeeeeee ee eeee eeee eeeeeee eeeeeeeee eee eee eeee eeeeeeeeee eeee eeee eeeeeeeee ee eee eeeee eeeeeeee. Me eeee, eeee 8-eeeeeeeeeeeeeee eeee ee eeee [M8 = (MM8)8Me], eee eeeeee eeeeeeeee ee eee eeeee eeeeeeeee eee ee eeeeeeee ee 8M MMM. Me eee eeeeee eeeee, eee eeeee eeeeeeeee ee eeeeeeeee ee (+)-eeeeeeeeeeeeeeee [(+)-‌88‌], eeeee eeee eeeeee eeee eeee ee eee eeeeeeeeeeee eeeeeee ee eeeeee eee eeeeeee eeeeee eeeee ‌88‌ eeee eeee eeeeeeeeeeee eeeeee. Mee eeeeeeeee eeee ee eee eeeeeeeeeee eee eeee ee eeeeeeeee ee eee eeeeeeeeee ‌88‌ ee eee eeeeeeee eeeeeee. Mee eeeee eeeee eeee eee eeeeeee eee eeeeeeeeee eeeeeeeee, eee eee eeeeeeeeee ee eee eeeeeee eeeeeeeeee eeeeeee eeeeeee eeee eee eeeeeeeee ee eee eeeeeeeeeeee eeeee eeeeeeeee. Me eeee, eee eeeeee eeeee eeeeee ee eee eeee-eeeeeeeeeee eeee ee eeee eeeeeeee eeeeeeeeeeeeee eeeeeee.

‌Meeeee 88‌ Meeeeeee Meeeeeeee eee Meeeeee Meeeeeeeee Meeeeeee ee (+)-Meeeeeeeeeeeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

(M)-8-Meeeee-8-eeeeeeeeeeee 8-Meeeeeeeeeeeeeee [‌88‌, M8 = eMe; M8 = (MM8)8Me]; Meeeeee Meeeeeeee:[‌88‌]

eMe8MMe (88.8 eM, 8.888 eeee), eeeeeeee (+)-‌88‌ (8.8 ee, 8.888 eeee), eee eee-8-eeeeee-8-eeeeeeeeeeee-8-ee (88.8 ee, 8.888 eeee) eeee eeeee ee e eeee ee eeeeeee eeeeeeeee (88.8 eM, 8.888 eeee) eee 8-eeeeeeeeeeeeeee eeee (88.8 ee, 8.888 eeee) ee MM8Me8 (8.8 eM) ee ee. Mee eeeeeee eee eeeeeee eee 88 e ee ee eee eeee eeeeeeee eeee eee. ee MeMMM8. Mee eeeeeee eeeee eee eeeeeeeee eee eee eeeeeee eeeee eee eeeeeeeee eeee Me8M (8 ×). Mee eeeeeeee eeeeeee eeeeee eeee eeeee (Me8MM8) eee eeeeeeee, eee eee eeeeeee eee eeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeeeeeeee MMM (eeeeee eee) ee eeeeee eee eeeeeeeeeeeee eeeee ‌88‌; eeeee: 88.8 ee (88%); 88.8% ee. Mee eeeeeeeeeeeeeeee eeeeeeee eeeeeee ‌88‌ eee eeee eeeeeeeee; eeeee: 88.8 ee (88%); 88% ee; eeeeeeeeeee (e): 8888. Meeeeeee ee eee eeeee ‌88‌ eee eeeeeeeee ee MMMM (Meeeeeeee MM-M, 8.8 eM · eee−8, eMeMM/eeeeeee 8:88): eM (M) 88.8 eee (88.88%), eM (M) 88.8 eee (8.88%).

References