Synthesis, Structural Characterization, and Conformational Bias in Solution of a Sterically Congested Pyrophosphite:~1 Experimental and Computational Evidence for Restricted Rotation about an sp~3-sp~3 P-O Single Bond

摘要

The synthesis and structural characterization of the sterically congested pyrophosphite 6-[(2,4,8,lO-tetrakis(l,l- dimethylethyl)-dibenzo[df][1,3,2]dioxaphosphepin-6-yl)oxy]-2,4,8,10-tetrakis (1,1-dimethylethyl)-dibenzo[df][1,3,2]-dioxaphosphepin, 3, is described. In solution at room temperature, a single species was observed that was consistent with a pyrophosphite structure without any evidence for the tautomeric diphosphine monoxide. Below the coalescence temperature (T c), O °C, three atropisomers were observed with relative absolute configurations of (R* ,R*,R*), (R*,S* ,R*), and (R* ,R*