We calculated the values of d, r, 1, 2, and  of 2oxabicyclo [2.1.1]hexanes from the X-ray data of compounds 5b, 9b. The related parameters for bicyclo [1.1.1]pentane 25 12b and bicyclo [2.1.1]heptanes 26, 27 were calculated from their X-ray data published in the literature. The corresponding parameters for ortho-substituted phenyl rings were calculated from the reported crystal data of two antihypertensive drugs -Valsartan and Telmisartan (Figure ). Analysis of this data revealed that geometric properties of 2-oxabicyclo[2.1.1]hexanes in general were indeed similar to those of the ortho-substituted phenyl ring. In particular, distance r in 2-oxabicyclo [2.1.1]hexanes was ca. 0.2 Å longer than that in the ortho-phenyl ring: 1.56-1.57 Å vs 1.38-1.44 Å (ortho-phenyl). The distance d between substituents in 2-oxabicyclo [2.1.1]hexanes was also ca. 0.5 A longer than that in the ortho-phenyl ring: 3.6 Å vs 3.0-3.1 Å (ortho-phenyl).