Reactivity of cyclic arsenites and phosphites: X-ray structures of bis(5,5-dimethyl-1,3,2-dioxarsenan-2-yl) ether and bis(2,4,8,10-tetra-tert-butyl-12H-dibenzo [d,g][1,3,2]dioxarsenocin-6-yl) ether

Abstract

Reaction of the chlorophosphite Cl[graphic omitted] 1 with cyclohexylamine gave the expected product (C₆H₁₁NH)[graphic omitted] 3 whereas the corresponding chloroarsenite 2 led to the bridged compound 12. When the reaction was performed in the presence of water, 1 gave the expected product H(O)[graphic omitted] 11 whereas 2 gave the oxo-bridged compound ([graphic omitted])₂O 13. The amino phosphite 3 underwent hydrolysis to afford the ring cleaved product 18 whereas the phenoxy phosphite 21 led to the ring preserved compound 11. In contrast, the corresponding phenoxy arsenite (PhO)[graphic omitted] 25 gave the oxo-bridged compound 13. Addition of perchloro-o-benzoquinone to the phosphite 23 was highly exothermic and afforded the phosphorane 29; however the corresponding arsenonate 27 reacted very sluggishly at room temperature and when heated gave an uncharacterizable mixture of products.

The identity of the title oxy-bridged compounds 13 and 15 obtained here has been confirmed by X-ray structure determination; the six-membered rings in 13 have a ‘chair’ conformation and the eight-membered rings in 15 have a ‘symmetrical anti’ conformation.