Reaction of diphenylborinic acid with pyridinium and phosphonium bisacyl methylides. Crystal and molecular structures of resulting <i>B</i>,<i>N</i>- and <i>B</i>,<i>P</i>-betaines

Abstract

Reaction of pyridinium and phosphonium 2-carboxy-1-formyl-2-oxoethylides with oxybis(diphenylborane) yields 5-(2-oxo-1-(pyridinio or phosphonio)ethylidene)-2,2-diphenyl-1,3-dioxa-2-borata-4-cyclopentanones, which represent novel types of boron nitrogen and boron phosphorus betaines, respectively. Crystals of 5-(2-oxo-1-pyridinioethylidene)-2,2-diphenyl-1,3-dioxa-2-borata-4-cyclopentanone,1a, are monoclinic, a = 15.589(3), b = 12.366(2), c = 20.1869(11) Å, β = 111.227(2)°, Z = 8 (two independent molecules), space group P21/a; and those of 5-[2-oxo-1-(triphenylphosphonio)ethylidene]-2,2-diphenyl-1,3-dioxa-2-borata-4-cyclo-pentanone,11, are monoclinic, a = 9.6922(7), b = 25.027(2), c = 11.3041(4) Å, β= 92.1418(13)°, Z = 4 (two independent molecules), space group P21. The structures were solved by direct methods and refined by full-matrix least-squares procedures to R (F, I 3σ(I)) = 0.047 and 0.042 (Rw (F2, all data) = 0.096 and 0.088), respectively, for 1a and 11.Key words: pyridinium ylides, phosphonium ylides, bisacyl methylide diphenylboron chelates, boron nitrogen betaines, boron phosphorus betaines, organoboron compounds, crystal structures.