Chlorophosphonates: Inexpensive precursors for stereodefined chloro-substituted olefins and unsymmetrical disubstituted acetylenes

New chlorophosphonates bearing a 1,3,2-dioxaphosphorinane ring which are us eful for the stereospecific synthesis of 5-chlorofurfuryl substituted olefi ns and chloro-substituted dienes have been obtained by an easy, inexpensive route. The utility of some of these in the synthesis of ferrocenyl- and an thracenyl-substituted unsymmetrical acetylenes has been explored. The struc tures of the phosphonates (OCH2CMe2CH2O)P(O)CH2(C4H2ClO) (4) and (OCH2Me2CH 2O)P(O)-(CH=CHCH(Cl)Ph (7) have been determined; in addition, the stereoche mistry of (5-chlorofurfuryl)-CH=CH(4-ClC6H4) (13b) and 2,4-Cl2C6H3-CH=CH-CH =C(Ph)Cl (14a) is unambiguously proved by the X-ray structure determination .