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 11 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 11 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. Bri‐ dged 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. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:320–326, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20097