61549-52-8Relevant academic research and scientific papers
Dinuclear ruthenium(I) complexes of the type [Ru2(CO) 4L2] with carboxylate or 2-pyridonate ligands: Evaluation as catalysts for olefin cyclopropanation with diazoacetates
Werle, Thorsten,Sch?ffler, Lutz,Maas, Gerhard
, p. 5562 - 5569 (2007/10/03)
Dinuclear ruthenium(I,I) carboxylate complexes [Ru2(CO) 4(μ-OOCR)2]n (R = CH3 (1a), C3H7 (1b), H (1c), CF3 (1d)) and 2-pyridonate complex [Ru2(CO)4(μ-2-pyridonate)2] n (3) catalyze efficiently the cyclopropanation of alkenes with methyl diazoacetate. High yields are obtained with terminal nucleophilic alkenes (styrene, ethyl vinyl ether, α-methylstyrene), medium yields with 1-hexene, cyclohexene, 4,5-dihydrofuran and 2-methyl-2-butene. The E-selectivity of the cyclopropanes obtained from the monosubstituted alkenes and the cycloalkenes decreases in the order 1b > 1a > 1d > 1c. The cyclopropanation of 2-methyl-2-butene is highly syn-selective. Several complexes of the type [Ru2(CO)4(μ-L1) 2]2 (4) and (5), [Ru2(CO)4(μ- L1)2L2] (L2 = CH3OH, PPh3) (6)-(9) and [Ru2(CO)4(CH 3CN)2(μ-L1)2] (10) and (11), where L1 is a 6-chloro- or 6-bromo-2-pyridonate ligand, are also efficient catalysts. Compared with catalyst 3, a halogen substituent at the pyridonate ligand affects the diastereoselectivity of cyclopropanation only slightly.
Synthetic studies on virantmycin. 2. Total synthesis of unnatural (+)-virantmycin and determination of its absolute stereochemistry
Morimoto, Yoshiki,Shirahama, Haruhisa
, p. 10631 - 10652 (2007/10/03)
The enantioselective total synthesis of (+)-virantmycin (1) has been achieved by means of the Sharpless asymmetric epoxidation of allylic alcohol 27 followed by an intramolecular epoxide opening of the exo epoxy alcohol 32 which was derived from the endo epoxy alcohol 28. The synthesis of (+)-1 has established that the absolute configuration of the natural product (-)-1 is shown to be 2R, 3R at the two chiral centers. Further, antiviral activities of the virantmycin analogs were also examined against influenza virus.
