in tetrahydrofuran dropwise addn. of an equimolar amt. of PhLi in THF to a soln. of the boronate in THF at -75°C with stirring; the mixture was allowed to reach room temp. for 1 h and was kept at 20-25°C overnight; performed under Ar;; concn. under vac.; the residue was dissolved in ether; filtration; evapn.; dissolving in hexane; filtration; distn.; elem. anal.;;