AND ABSTRACT Alcohols and amines are valuable pharmacophores found in countless pharmaceutical agents and bioactive small molecules. Accordingly, expedient access to enantioenriched molecules bearing these pharmacophores is of tremendous synthetic and medicinal interest. This is especially true for tertiary alcohols and carbinamines, which are generally difficult products to access via modern asymmetric catalysis. One method for the synthesis of chiral alcohols and amines is through carbenoid insertion into the ? C-H bonds of these functional groups, forging a carbon-carbon bond in the process; however, currently precious metal catalysts are limited in their capacity to execute these transformations with efficient yields and enantioselectivities. As engineered hemoproteins continue to perform increasingly difficult asymmetric reactions of carbenoids, it is evident that they provide an attractive solution to this longstanding challenge. This proposal focuses on the development of such a protocol, which is unknown in natural systems and represents a powerful extension of enzymatic iron-carbenoid chemistry.
The specific aims are: (1) to evolve existing hemoproteins to perform carbenoid insertions into the ? C-H bonds of primary alcohols and carbinamines to form enantioenriched small molecules via directed evolution; (2) to extend this protocol to secondary alcohols and combine this reaction with alcohol racemization to furnish a dynamic kinetic resolution to access enantioenriched tertiary alcohols.
These aims will be initiated using the panoply of heme protein mutants available in the Arnold Lab using directed evolution methods such as error-prone PCR and site-saturation mutagenesis. Such a method provides a cogent solution to extant problems in C-H functionalization, further information about enzymatic carbene transfer reactivity which can be applied to further synthetic problems, and a green and sustainable route to valuable pharmacophores.
Biocatalysis is an attractive strategy for the synthesis of bioactive molecules because the catalyst sources are inexpensive and sustainable relative to precious metal catalysts, allowing for green and renewable routes to valuable pharmaceutical agents. Alcohols and amines are valuable pharmacophores found in countless commercial drugs; accordingly, reactions to synthesize these valuable motifs are of massive importance to the development of new treatments for diseases. The proposed research focuses on developing a biocatalyst capable of forming carbon-carbon bonds through C-H activation to produce chiral alcohols and amines, providing a new, powerful, and sustainable route to these products.
