1407162-86-0Relevant articles and documents
Spiroligozymes for transesterifications: Design and relationship of structure to activity
Kheirabadi, Mahboubeh,?elebi-?l?üm, Nihan,Parker, Matthew F. L.,Zhao, Qingquan,Kiss, Gert,Houk,Schafmeister, Christian E.
supporting information, p. 18345 - 18353 (2013/01/15)
Transesterification catalysts based on stereochemically defined, modular, functionalized ladder-molecules (named spiroligozymes) were designed, using the inside-out design strategy, and mutated synthetically to improve catalysis. A series of stereochemically and regiochemically diverse bifunctional spiroligozymes were first synthesized to identify the best arrangement of a pyridine as a general base catalyst and an alcohol nucleophile to accelerate attack on vinyl trifluoroacetate as an electrophile. The best bifunctional spiroligozyme reacted with vinyl trifluoroacetate to form an acyl-spiroligozyme conjugate 2.7 × 103-fold faster than the background reaction with a benzyl alcohol. Two trifunctional spiroligozymes were then synthesized that combined a urea with the pyridine and alcohol to act as an oxyanion hole and activate the bound acyl-spiroligozyme intermediate to enable acyl-transfer to methanol. The best trifunctional spiroligozyme carries out multiple turnovers and acts as a transesterification catalyst with k1/kuncat of 2.2 × 103 and k2/kuncat of 1.3 × 102. Quantum mechanical calculations identified the four transition states of the catalytic cycle and provided a detailed view of every stage of the transesterification reaction.
