Reference

Homogeneous Hydrogenation of Benzo[b]thiophene by Use of Rhodium and Iridium Complexes as the Catalyst Precursors: Kinetic and Mechanistic Aspects

Homogeneous Hydrogenation of Benzo[b]thiophene by Use of Rhodium and Iridium Complexes as the Catalyst Precursors: Kinetic and Mechanistic Aspects. Herrera, Veronica; Fuentes, Alberto; Rosales, Merlin; Sanchez-Delgado, Roberto A.; Bianchini, Claudio; Meli, Andrea; Vizza, Francesco (Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020-A, Venez.). Organometallics, 16(11), 2465-2471 (English) 1997 American Chemical Society. CODEN: ORGND7. ISSN: 0276-7333. DOCUMENT TYPE: Journal CA Section: 67 (Catalysis, Reaction Kinetics, and Inorganic Reaction Mechanisms) Section cross-reference(s): 22, 29, 75, 78 [M(COD)(PPh3)2]PF6 (M = Rh, 1a; Ir, 1b) are highly efficient precatalysts for the homogeneous hydrogenation of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT). Both complexes react rapidly with BT and H2 to produce the corresponding [M(H)2(h1(S)-BT)2(PPh3)2]PF6 (M = Rh, 2a; Ir, 2b), which enter the catalytic cycle. In the case of Ir, the catalysis is more conveniently carried out using 2b, which is stable enough to be isolated pure. Kinetic and mechanistic studies of BT hydrogenation were carried out by using 1a and 2b as the catalyst precursors in 1,2-dichloroethane soln. at 40°. For both complexes, the reaction proceeds according to the rate law r = kcat[M][H2], where kcat = k1K3/(1 + K3[H2]). All of the exptl. data are consistent with a general mechanism in which the transfer of the hydrides to coordinated BT in [M(H)2(h2(C:C)-BT)(PPh3)2]PF6 is the rate-detg. step of the catalytic cycle. [Ir(H)2(h1(S)-DHBT)2(PPh3)2]PF6 was obtained as a stable end product of the Ir catalysis and was characterized by spectroscopic anal. and by x-ray diffraction. The coordination geometry around the Ir atom consists of a distorted octahedron with mutually cis S-bonded DHBT, cis hydrides, and trans triphenylphosphines.

Synthesis of potentially biological active benzothieno-oxazinones

Synthesis of potentially biological active benzothieno-oxazinones. Oremek, G.; Seiffert, U.; Siede, W. (Johann Wolfgang Goethe-Univ.Except for chemicals metioned above, 1467-79-4 is also used., Frankfurt am Main D-6000/70, Fed. Rep. Ger.). Pharmazie, 39(8), 574-5 (German) 1984. CODEN: PHARAT. ISSN: 0031-7144. DOCUMENT TYPE: Journal CA Section: 28 (Heterocyclic Compounds (More Than One Hetero Atom)) Section cross-reference(s): 27 Benzo[b]thiophenecarboxylate dioxides I (R = H, NO2, R1 = OH) reacted with R2R3NCN [II, R2 = R3 = Me, R2R3 = (CH2)4] to give isomeric benzothienooxazinones III and IV in 20-40% yield and benzothiophenecarboxamides I [R1 = R2R3NCCl:N) (V) in 45% and 37% yield, resp. I (R = H, R1 = Cl) reacted with II (R2 = R3 = Me) to give 45% III and 37% V. .