P(RNCH₂CH₂)₃N: Superbasic and Catalytic Cages

Abstract

In contrast to acyclic P(NR₂)₃, the title pro-azaphosphatrane cages (first reported from our laboratories) are exceedingly strong nonionic bases that protonate to give the extraordinarily weak acids HP(RNCH₂CH₂)₃N⁺ (pK_a in MeCN, ∼41). Thus we have found that commercially available P(MeNCH₂CH₂)₃N is a superior nonionic base for the synthesis of porphyrins, alkenes, C-monoalkylation of esters and β-hydroxy nitriles. We have also discovered that P(RNCH₂CH₂)₃N cages function as superior catalysts for the synthesis of β-hydroxy nitriles, α,β-unsaturated nitriles and silyl-protected alcohols. Protective acylations of alcohols are very efficiently promoted by P(MeNCH₂CH₂)₃N.

Keywords::

• pro-azaphosphatranes
• nonionic base
• catalysis
• silylation
• acylation