1-Methylcyclohexene, reaction with complex

High catalytic activities, with turnovers of up to 9(X) cycles min , is displayed in the transfer hydrogenation of a,p-unsaturated ketones, such as benzylideneacetone and chalcone, using 2-propanol and catalytic amounts of [Ir(3,4,7,8-Me4-phen)COD]Cl (phen = 1,10-phenanthroline COD = 1,5-cyclo-octadiene) in a weakly alkaline medium. Other Ir-chelated complexes are also active catalysts in this reaction, with over 95% selectivity for the 1,4-reduction mode. Divalent lanthanide derivatives, such as Sml2 or Ybh in stoichiometric quantities, in THF and t-butyl alcohol or methanol reduce ethyl cinnamate and cinnamic acid to give the saturated derivatives. " Similarly, 3-methylcyclohexenone is reduced to 3-methylcyclohexen-l-ol in 67% yield, but a,p-unsaturated aldehydes are nonselectively reduced with these systems. 

Optical resolution of some hydrocarbonds and halogeno compounds by inclusion complexation with the chiral host (9a) has been accomplished.11,12 Preparation of optically active hydrocarbons is not easy and only a few example of the preparation of optically active hydrocarbons have been reported. For example, optically active 3-phenylcyclohexene has been derived from tartaric acid through eight synthetic steps.11 Although one-step synthesis of optically active 3-methylcyclohexene from 2-cyclo- hexanol by the Grignard reaction using chiral nickel complex as a catalyst has been reported, the enantiomeric purity of the product is low, 15.9%.11 In this section, much more fruitful results by our inclusion method are shown. 

Bromo-2-thioaryloxy-3-methylcyclohexen-l-one, 2a, is an achiral compound. Its conformation can be fixed in a chiral twisted form in the solid state, but it forms racemic crystals, and hence the solid-state reaction produces a racemic mixture of (—) and (+ )3a. A method for achieving an enantioselective reaction is to form an inclusion complex with a chiral host compound, (— )-(R,R)-( — )-fran.s-2,3-bis(hydroxy diphenyl methyl)-1,4-dioxa spiro-[4,4]nonane, ( — )-4. In a typical experiment, a benzene (5 mL) and hexane (5 mL) solution of (— )-4 and 2a left at room temperature for 24 h gave a 1 1 inclusion compound of (-)-2a and 4 as colorless crystals [38]. 

Chan and co-workers have developed a novel ruthenium complex (81, Figure 16) which catalyses the epoxidation of cyclic alkenes with molecular oxygen in excellent yield under mild reaction conditions. Cyclopentene (90% yield), cyclohexene (up to 90% yield), methylcyclohexene (90% yield), phenylcyclohexene (78% yield), and cyclooctene (97% yield) are all readily epoxidized <2003CC1058>. 

Bromo-2-thioaryloxy-3-methylcyclohexen-l-one, 2a, is an achiral compound. Its conformation can be fixed in a chiral twisted form in the solid state, but it forms racemic crystals, and hence the solid-state reaction produces a racemic mixture of (—) and (+ )3a. A method for achieving an enantioselective reaction is to form an inclusion complex with a chiral host compound, (— — )-... 

Various oxidations with [bis(acyloxy)iodo]arenes are also effectively catalyzed by transition metal salts and complexes [726]. (Diacetoxyiodo)benzene is occasionally used instead of iodosylbenzene as the terminal oxidant in biomimetic oxygenations catalyzed by metalloporphyrins and other transition metal complexes [727-729]. Primary and secondary alcohols can be selectively oxidized to the corresponding carbonyl compounds by PhI(OAc)2 in the presence of transition metal catalysts, such as RuCls [730-732], Ru(Pybox)(Pydic) complex [733], polymer-micelle incarcerated ruthenium catalysts [734], chiral-Mn(salen)-complexes [735,736], Mn(TPP)CN/Im catalytic system [737] and (salen)Cr(III) complexes [738]. The epox-idation of alkenes, such as stilbenes, indene and 1-methylcyclohexene, using (diacetoxyiodo)benzene in the presence of chiral binaphthyl ruthenium(III) catalysts (5 mol%) has also been reported however, the enantioselectivity of this reaction was low (4% ee) [739]. 

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