optionally alkali metal carbonate phase transfer catalyst and first solvent are combined with second solvent the amounts of reactants used in triphasic embodiments are essentially the same as in biphasic embodiments however an excess up to about a 100 excess of irb 23 is preferred the volume of second solvent is about one quarter to one half of the volume of first solvent work up of the reaction mixture is analogous to that in biphasic embodiments the first solvent phase is separated and combined with first solvent phase obtained by optional extracting of the second solvent phase with first solvent the first solvent phases can the be treated and the irb 03 isolated as in biphasic embodiments in another embodiment the present invention provides a novel synthesis of irbesartan analogues thereof and especially precursors therefor e g trityl irbesartan including the step of reacting a reacting a valerimidate derivative with an amine to form an ester intermediate and further reacting the ester intermediate with an amine to form 2 butyl 3 2 u2032 1 trityl 1h tetrazole 5 yl biphenyl 4 yl methyl 1 3 diazaspiro 4 4 non 1 en 4 one the step is carried out in the presence of an acid preferably the.