470664-03-0Relevant articles and documents
Synthesis of cross-conjugated olefins from alkynes: Regioselective C-C bond formation between alkynes
Chin, Chong Shik,Lee, Hyungeui,Park, Hyeyun,Kim, Mieock
, p. 3889 - 3896 (2008/10/08)
Reactions of cis-dihydrido complex [Ir(H)2(NCCH3)2(PPh3)2] + (1) with HC≡CH and RC≡CH (R = C6H5, p-C6H4CH3, cyclohex-1-enyl, C(CH3)=CH2, C(CH3)3) produce cross-conjugated hexatrienes (RCH=C(CH=CH2)2, R-HEX) and octatetraenes (H2C=CH-CR=CH-C(-CH= CH2)=CHR, R2-OCT). Two molecules of HC≡CH are inserted into Ir-H bonds of 1 to give cis-bis(ethenyl) complex [Ir(CH==CH2)2(NCCH3)2(PPh3 )2]+ (2), which reacts with RC≡CD to produce both R-HEX-d1 (RCD=C(CH=CH2)2) and R2-OCT-d2 (H2C=CH-CR=CD-C(-CH= CH2)=CDR). R-HEX are exclusively obtained from the reactions of RC≡CH with [Ir(CH= CH2)2(CO)2(PPh3)2]+ (3). Alkynyl cis-bis(ethenyl) complexes Ir(CH=CH2)2(C≡CR)(CO)(PPh3)2 (4, R = C6H5 (a), p-C6H4CH3 (b), cyclohex-1-enyl (c)) react with D+ to give η4-R-HEX-d1 complexes [Ir(η4-RCD=C(CH=CH2)2)(CO)(PPh3) 2]+ (5-d1) from which R-HEX-d1 are obtained in the presence of a base. Di- and trinuclear alkynyl-bis(alkenyl) complexes [L5Ir-C≡Cp-C6H4-C≡C-IrL5 ] (7, L5 = (-CH=CH2)2(CO)(PPh3)2) and [L5Ir-C≡C-m,m-C6H3-(C≡C-IrL5 )2] (8, L5 = (-CH=CH2)2(CO)(PPh3)2) react with H+ to produce extended cross-conjugated olefins, p-C6H4-(HEX)2 and m,m-C6H3-(HEX)3, respectively, in high yields. Plausible reaction pathways involve alkenyl-vinylidene complexes that undergo the C-C bond formation reaction between the two hydrocarbyl ligands to produce the cross-conjugated olefins.
