New 7-phosphanorbornenes derived from 2-methyl-1-phenyl- and 1-cyclohexyl-3-methyl-2,5-dihydro-1H-phosphole 1-oxides

Novel 7-phosphanorbornene derivatives, such as 4, 5, 10, and I I were synthesized utilizing 1-phenyl-2-methyl-2,5-dihydro-1H-phosphole oxide (1) and 1-cyclohexyl-3-methyl-2,5-dihydro-1H-phosphole oxide (7) as the starting materials. Products 4 and 10 were prepared by trapping the corresponding phosphole oxide intermediates (3 and 9, respectively) by N-phenylmaleimide, while 5 and I I were obtained by the dimerization of 3 and 9, respectively. The trapping reaction was studied in details; on one hand, bromo-2,3-dihydro-1H-phosphole oxides (6-1 and 6-2) were pointed out as the intermediates, on the other hand, the trapping reaction was optimized. Bridged P-heterocycles 4, 5, 10, and 11 were tested in the fragmentation-related phosphorylation of methanol. Hydrogenation of phosphanorbornenes 4 and 5 led to the corresponding phosphanorbornanes (12 and 14, respectively) and to a reductive type of retro cycloaddition. (c) 2005 Wiley Periodicals, Inc.