Organoborate Salts Derived From Tris (Hydroxymethyl) Phosphine And Triarylphosphine-catalyzed Acetalization

The first part of this paper studies synthesis of organoborate salts derived from tris(hydroxymethyl)phosphine.Produced by organobozonic acids and triol compounds,organoborate salts are stable to air and good solids.These compounds can be applied to a variety of transition-metal-catalyzed C-C coupling reactions.We found that tetrabutyl ammonium hydroxide as a base and below 0 ℃,tetrakis(hydroxymethyl)phosphonium sulfate(THPS)can degrade into tris(hydroxymethyl)phosphine,it can be further reacted with organic boric acids,generating organoborate salts containing-phosphorus.The yield are 15%-86%.These organoborate salts are good white solids.All of them are air and / or water-sensitive compounds,they can easy to store and crystal.This synthetic method can be applied to electron-rich aromatic boric acids,electron-deficient aromatic boric acids,aliphatic boric acids and heterocyclic boric acids.In addition to the individual production rates are low,the rest of the production rates are between 51% and 86%.The second part researches triarylphosphine-catalyzed acetalization.We found that some common alcohols can react with triphenylphosphine fluoboric acid salt and aldehydes in the 2-methyl tetrahydrofuran,stirring overnight(15-20 h)at room temperature can produce ?-alkoxyphonium salts.With the dihydric alcohol,such as glycol and pinacol instead of ethanol,catalyzed by triphenylphosphine fluoboric acid salt can generate the corresponding acetals.Thus providing a simple and mild synthesis route to protect carbonyl groups.We also synthesized2-(diphenylphospino)benzoic acid hydrobromide.It can replace triphenylphosphine fluoboric acid salt,used as a catalyst to produce acetals.The separation of acetals is easier.