476 ENOLS AND ENOLATES 18.16 The enolate of dibenzyl ketone adds to methyl vinyl ketone in the conjugate addition step nOCH C6HS C6H5 H2C-CHCCH3CH, OH C&HSCH- CCHCH CHCHCCH Dibenzyl ketone Methyl vinyl ketone 1.3-Diphenyl-2, 6-heptanedione CBH CH,CCHCAH5 C6HSCH-CCHCH HC=CHCCH H,C--CHCCH3 The intramolecular aldol condensation that gives the observed product is HC、CH-C noCH CHCH CH,OH CHC&H HO CH,-CH, 1.3-Diphenyl-2, 6-heptanedione 18.17 A second solution to the synthesis of 4-methyl-2-octanone by conjugate addition of a lithium dialkylcuprate reagent to an a, B-unsaturated ketone is revealed by the disconnection shown CH, CH,CH,CH,CHCH, CCH3 CHa CH,CH, CH,CH=CHCCH3 H3 Disconnect this bond According to this disconnection, the methyl group is derived from lithium dimethylcuprate CH, CH, CH, CH, CH=CHCCH2 t LiCu(CHi) CH CH,CH,CH,CHCH, CCH 3-Octen-2-one Lithium 4.Methyl-2-octanone methy cuprate 18.18 (a) In addition to the double bond of the carbonyl group, there must be a double bond elsewher in the molecule in order to satisfy the molecular formula Cho (the problem states that the Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website18.16 The enolate of dibenzyl ketone adds to methyl vinyl ketone in the conjugate addition step. via The intramolecular aldol condensation that gives the observed product is 18.17 A second solution to the synthesis of 4-methyl-2-octanone by conjugate addition of a lithium dialkylcuprate reagent to an ,-unsaturated ketone is revealed by the disconnection shown: According to this disconnection, the methyl group is derived from lithium dimethylcuprate. 18.18 (a) In addition to the double bond of the carbonyl group, there must be a double bond elsewhere in the molecule in order to satisfy the molecular formula C4H6O (the problem states that the CH3CH2CH2CH2CH CHCCH3 O O LiCu(CH3 CH3CH2CH2CH2CHCH2CCH3 )2 3-Octen-2-one Lithium dimethylcuprate 4-Methyl-2-octanone CH3 CH3CH2CH2CH2CH CHCCH3 O O CH3CH2CH2CH2CHCH2CCH3 Disconnect this bond. CH3 CH3 1,3-Diphenyl-2,6-heptanedione C6H5CH2 C CHC6H5 O O CH2 CH2 CH3C H3C C6H5 C C CHC6H5 O HO CH2 CH2 CH 3-Methyl-2,6-diphenyl-2- cyclohexen-1-one NaOCH3 CH3OH H2O C6H5 C6H5 O H3C C6H5CH2CCHC6H5 H2C O O CHCCH3 C6H5CH2CCHC6H5 O H2C O CHCCH3 Dibenzyl ketone Methyl vinyl ketone 1,3-Diphenyl-2,6-heptanedione NaOCH3 CH3OH C6H5CH2CCH2C6H5 H2C CHCCH3 O O C6H5CH2CCHC6H5 CH2CH2CCH3 O O 476 ENOLS AND ENOLATES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website