Bicycloannulation of C=N Double Bonds through Organotin-Aided Three Component Coupling. A Short and Stereoselective Synthesis of (±)-allo-Berbane and (±)-allo-Yohimbane Systems
Catalytic asymmetric allylation of aldehydes with allylic trialkylstannanes was achieved with BINAP•AgOTf complex as catalyst. The chiral silver(I) catalyst was readily prepared by stirring an equimolar mixture of BINAP and silver(I) triflate in THF at room temperature. The allylation of a variety of aromatic and α,β-unsaturated aldehydes resulted in high yields and remarkable enantioselectivities
Free radical allylations of α-seleno carbonyl compounds with tributyl-substituted 2,4-pentadienyltin, 2-methyl-2-propenyltin, 2-butenyltin, and 3-methyl-2-butenyltin, are described. Such successful C–C bond formations, in particular with the 2-butenyltin and the 3-methyl-2-butenyltin, are owing to the high reactivity of the α-carbon radical, generated from α-seleno carbonyl compounds, toward allylic tin compounds.
An Easy Access to Stereodefined 2-Pentenyltins by Partial Hydrogenation of 2,4-Pentadienyltins with Diazene
作者:Yutaka Nishigaichi、Noriyuki Ishida、Akio Takuwa
DOI:10.1246/bcsj.67.274
日期:1994.1
Tributyl-(2-pentenyl)tins were readily prepared in high yield by hydrogenation of tributyl-(2,4-pentadienyl)tins with diazene generated from 2,4,6-triisopropylbenzenesulfonohydrazide. The terminal double bond was selectively hydrogenated in the conjugated diene system. The stereochemistry of the internal double bond was completely retained.
Bicycloannulation of C=N Double Bonds through Organotin-Aided Three Component Coupling. A Short and Stereoselective Synthesis of (±)-<i>allo</i>-Berbane and (±)-<i>allo</i>-Yohimbane Systems
Organotin-aided three component couplings of C=N double bonds with 2,4-pentadienyl and α,β-unsaturated acyl groups followed by intramolecular Diels–Alder reactions result in highly stereoselective bicycloannulation of the C=N double bonds to afford allo-berbane and allo-yohimbane systems in one-flask operation.
Half-Sandwich Ruthenium-Phosphine Complexes with Pentadienyl and Oxo- and Azapentadienyl Ligands
作者:Amira Reyna-Madrigal、Anabel Moreno-Gurrola、Odilia Perez-Camacho、M. Elena Navarro-Clemente、Patricia Juárez-Saavedra、Marco A. Leyva-Ramirez、Atta M. Arif、Richard D. Ernst、M. Angeles Paz-Sandoval
DOI:10.1021/om300657z
日期:2012.10.22
2)RuX(PPh3)2 [X = Cl, (2); H, (3)]. The steric congestion in 2 is most effectively relieved by formation of the cyclometalated complex (η5-CH2C(Me)CHC(Me)CH2)Ru(C6H4PPh2)(PPh3) (4). Addition of 1 equiv of PHPh2 to (η5-CH2CHCHCHCH2)RuCl(PPh3)2 (1) affords the chiral complex (η5-CH2CHCHCHCH2)RuCl(PPh3)(PHPh2) (5), while compound (η5-CH2C(Me)CHC(Me)CH2)RuCl(PPh3)(PHPh2)] (6) is directly obtained from