Abstract
AbstractPhosphonium salts are compounds of great synthetic interest, both as reactants in numerous reactions and, more recently, as organocatalysts in enantioselective organic transformations and metal-free catalytic processes. This chapter is an update to the previously published Section 42.12 and is dedicated to the synthesis of alkylphosphonium salts, meaning that the phosphorus atom is connected to at least one alkyl substituent. The focus is on reports in the literature from 2010 to 2020. Key developments during this period that are covered include fluorinated phosphonium salts, phosphonium-based frustrated Lewis pairs (FLPs), and chiral alkylphosphonium salts. Advances in catalytic and asymmetric phase-transfer catalysis are also discussed.