Octan-2-one

PHOTOCYCLIZATION OF AN ENONE TO AN ALKENE 6-M THYLBICYCL0[4.2.0]0CTAN-2-0NE (Bicyc1o[4.2.0]octan-2-one, 6-methy1-)... 

Photolysis of bicyclo[2.2.2]octan-2-one (A) gives B in good yield. When A labeled as shown is used, the aldehyde group carries deuterium to the extent of 51.7%. Write a mechanism to account for the overall transformation. Calculate the isotope effeet for the step in which hydrogen-atom transfer occurs. What mechanistic conclusion do you... 

Exclusive exo (equatorial) attack is also observed with bicyclo[3.2.1]octan-3-one (5), whereas addition of methylmagnesium iodide to bicyclo[3.2.1]octan-2-one (7) affords the diastereomeric products in almost equal amounts5i. The cyclohexanone moiety of both bicyclic ketones 5 and 7 adopts a chair conformation and therefore the 3,5-diaxialethano bridge in... 

As a first step in the prepartion of polymers patterned after the repeating unit of nonactin 56, Moore and Kelley53 synthesized 3,8-dioxabicyclo[3.2.1 ]octan-2-one 57 and its corresponding polyester 58. The monomer was prepared from 5-hydroxy-methylpyran-2-carboxylic acid in overall yield of 20%. It was heated with a catalytic amount of tert-butoxytitanate under nitrogen for 3 hr at 100 °C. The temperature... 

Mehta et al. also studied the facial selectivities of 5,6-exo,eji o-disubstituted bicyclo[2.2.2]octan-2-ones 18 [75, 78]. These systems are related to the 2,3-exo,ex( -disubstituted 7-norbomanones 14, but differ in the direction of the carbonyl n face. Hydride reduction of 5,6-exo,ex( -disubstituted bicyclo[2.2.2] octan-2-ones (18) with NaBH and DIBAL-H and methylation with MeLi were smdied [75, 78],... 

Hydroxy-2-pentynoic acid, 56, 51 7-Hydroxy-4,4,5,7-tetramethylbicyclo-[4.2.0] octan-2-one, 57, 115 V-Hydroxy-l-(p-tolylsulfonyl)meth-animidoyl chloride, 57, 100 11-HYDROXYUNDECANOIC LACTONE, 58, 98, 100... 

Scheme 4 A La3 +-catalyzed deprotection reaction of 6-exo-acetoxybicyclo[2.2.2]octan-2-one, where the mild nature of the transesterification conditions does not promote rearrangement of the product (ref. 44).

Although there is evidence that quaternary ammonium salts are cleaved by sodium borohydride at high temperature [7], initial studies suggested that the quaternary ammonium borohydrides might have some synthetic value in their selectivity, e.g. aldehydes are reduced by an excess of the quaternary ammonium salts under homogeneous conditions in benzene at 25 °C, whereas ketones are recovered unchanged and are only partially reduced at 65 °C [2], The reduction of esters also requires the elevated temperature, whereas nitriles are not reduced even after prolonged reaction at 65 °C. Evidence that the two-phase (benzene water) reduction of octan-2-one by sodium borohydride was some 20-30 times faster in the presence of Aliquat, than in the absence of the catalyst [8], established the potential use of the mote lipophilic catalysts. 

A good example of clearable and non-clearable stereocentres is found in the two following stereoisomers of bicylo[3.3.0]octan-2-one, in which the shape of the molecule forces the attack of the nucleophile to the carbonyl group from the convex face (attack at the (3-face). 

Nucleophilic addition of ester-derived enolate to the bicyclo[3.3.0]octan-2-one system of diacetone glucos-3-ulose usually occurs at the convex jS-face of the carbonyl (as for other nucleophiles), except for senecioate-derived enolate (from 3-methyl cro-tonate) for which a-attack in diethylether solvent is in contrast to the jS-face attack in THF the reason for this anomalous behaviour is not clear. 

Similarly, azabicyclo[3.2.2]nonanes 426 were produced from bicyclo[2.2.2]octan-2-ones 425 (equation 180). 

Cis-RuClj(phen)3 is made as black crystals by reaction of RUCI3 with (phen). As CM-RuCl2(phen)3/aq. yO / BuOH or 1,2-dimethoxyethane it stereospecifically epoxidised oleic acid to 9, 10-epoxyoctadecanoic acid [833] The reagent cis-RuCljlphey /aq. Li(C10)/CH3Cl2 oxidised dipropylether to propylpropionate, tet-rahycfiopyran to 6-valerolactone, adamantane to adamantan-l-ol and adamantanone, and octan-2-ol to octan-2-one [834],... 

The system [RuCl(dppp)j]Vaq. Oxone /CHjClj oxidised primary and secondary alcohols to aldehydes and ketones ([Ru(H30) PW (0)3, ] , RuClj and cis-RuCydmso) also catalysed the reaction) [933], while fra i-RuCl2(dppp)2 and [RuCl(ppy)J+/aq. Li(C10)/CH3Cl3, like c/x-RuC phen), oxidised octan-2-ol to octan-2-one [934], As [RuCKdppp) ] or [Rua(ppy)2] /PhlO/CH3Clj they epoxidised nor-bomene, styrene, stilbene, hex-l-ene and franx-hex-2-ene a number of by-products (alcohols, aldehydes and ketones) were also formed. Kinetic measurements and experiments using suggested the intermediacy of [Ru (0)Cl(dppp)J [932, 935],... 

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