Figure 3.

(a) Scope of trifluorodiazo alkanes for carbene B–H insertion catalyzed by BOR-CF₃. Reactions were performed in M9-N (pH 7.4) suspensions of E. coli cells expressing BOR-CF₃ (OD₆₀₀ = 20). Standard reaction conditions were 10 mM borane substrate 1, 7.5 mM diazo substrate n, room temperature under anaerobic conditions. The absolute configuration of 2a was determined to be R based on the optical rotation of the derivatized alcohol (see the Supporting Information, section VII). (b) Preparative scale synthesis (0.2 mmol scale) and the derivatization of 2a to boronic acid 2c.