I. Stereochemistry of cyclopropane formation involving group (IV) organometallic complexes. II. Slower stoichiometric and faster catalytic reduction of aldehydes by the PPh(3) substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph(2)-3,4-Tol(2)(eta

The reaction of (Z)-HDC=CHCH(OCH3)C6H5 with Cp2Zr(D)Cl followed by BF3•OEt2, gave two phenylcyclopropanes, both having cis deuterium. This stereochemical outcome requires inversion of configuration at the carbon bound to zirconium and is consistent with a W-shaped transition state structure for cyclopropane formation. In a Kulinkovich hydroxycyclopropanation, trans-3-deutero-l-methyl- cis-2-phenyl-1-cyclopropanol was formed stereospecifically from Ti(O- i-Pr)4, ethyl acetate, EtMgBr, and trans-beta-deuterostyrene. This stereochemistry requires retention of configuration at the carbon bound to titanium and is consistent with frontside attack of the carbon-titanium bond on a carbonyl group coordinated to titanium. In a de Meijere cyclopropylamine synthesis, a 3:1 mixture of N,N-dimethyl-N-(trans -3-deutero-trans-2-phenylcyclopropyl)amine and N,N-dimethyl-N-(cis-3-deutero-cis-2-phenylcyclopropyl)amine was formed from Ti(O-i-Pr)4, DMF, Grignard reagents, and trans-beta-deuterostyrene. This stereochemistry requires inversion of configuration at the carbon bound to titanium and is consistent with a "W-shaped" transition structure for ring closure.;Isomerization of trans-3-deutero-r-1-methyl- cis-2-phenylcyclopropan-1-ol to three isomeric cyclopropanols was facilitated by reaction with a mixture of Ti(O-i-Pr) 4 and BF3•OEt2. This cyclopropanol to cyclopropanol rearrangement involves reversible ring opening to a beta-titanaketone.;The phosphine substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph2-3,4Tol2(eta5-C4COH)]Ru(CO)(PPh 3)H displayed behavior significantly different than that of the dicarbonyl analog, including the failure to form an unreactive diruthenium complex analogous to the Ru(CO)2 Shvo catalyst. [2,5-Ph2-3,4-Tol 2(eta5-C4COH)]Ru(CO)(PPh3)H shows no apparent reduction of aldehydes in the absence of a trap, but exchanges deuterium between the deuteride of [2,5-Ph2-3,4-Tol2(eta 5-C4COD)]Ru(CO)(PPh3)D and the aldehydic hydrogen of p-tolualdehyde. This provides evidence that aldehyde reduction occurs, but is reversible.;[2,5-Ph2-3,4-Tol2(eta5-C4COH)]Ru(CO)(PPh 3)H stoichiometrically reduces aldehydes and ketones in the presence of a pyridine trap to produce alcohols and a ruthenium pyridine complex, with a rate law of -d[Ru]/dt = k[RCH=O]1[Ru]1[pyridine]0. The observation of deuterium kinetic isotope effects on substitution of the acidic and hydridic protons of [2,5-Ph2-3,4-Tol2(eta 5-C4COH)]Ru(CO)(PPh3)H are consistent with concerted transfer of hydrogen to aldehydes during reduction. This catalyst hydrogenates aldehydes under mild temperature and pressure conditions. A rate law of - d[RCH=O]/dt = k[RCH=O]1 [Ru]1[H2]0 was obtained. While the Ru(CO)2 Shvo catalyst shows little activity under these conditions, it surpasses 12,5-Ph2-3,4-Tol2(eta 5-C4COH)]Ru(CO)(PPh3)H at elevated temperatures and pressures. [2,5-Ph2-3,4-Tol2(eta5-C 4COH)]Ru(CO)(PPh3)H shows high chemoselectivity for catalytic hydrogenation of aldehydes over ketones, while the Shvo catalyst is much less selective.