Tertiary Alkylations of Aldehydes, Ketones or Imines Using Benzylic Organoboronates and a Base Catalyst

Abstract

The KHMDS-catalyzed tertiary alkylation of aldehydes, ketones or imines using tertiary benzylic organoboronates is reported. This protocol permitted the use of tertiary benzylic alkylboronates as the tertiary alkyl anion for construction of highly congested contiguous sp3 carbon centers. The mild and transition-metal-free reaction conditions are attractive features of the protocol.

Transition‐Metal‐Free Cross‐Coupling by Using Tertiary Benzylic Organoboronates

“…Here, we report tertiary alkylative cross‐coupling of alkyl or aryl electrophiles using benzylic organoboronates (Figure 1 D). [7] The reaction involves the generation of tertiary alkyl anions from organoboronates in the presence of an alkoxide base and then their substitution reactions under mild and transition‐metal‐free conditions. This protocol allows the simple and efficient construction of quaternary carbon centers.…”

“…[6a] PhLi showed moderate reactivity (entry 6). [5] The effect of the leaving group of the alkyl electrophile was also evaluated (Table 1, entries [7][8][9][10][11]. The reaction with secondary alkyl fluoride resulted in recovery of the substrate (entry 7).…”