1559T_ch18_323-34311/3/0511:12Page328 EQA 328.Chapter 18 ENOLS,ENOLATES,AND THE ALDOL CONDENSATION:B-UNSATURATED ALDEHYDES AND KETONES 32 33.a (b)3-Pentanone H2C=CHCH3 (d)3-Pentanone +H2C-C(CHa) CH.CH(CHz akylation sequences.The new carbon carbon bond is marked with (a)(CHaC-CHCHCHCHO ac=H-○ u te and iodomethan 32. 35. Illustrated with cyclohexanone: Before the reaction between cyclohexanone enolate and iodomethane has gone to completion, a mixture is present containing CH3 O CH3I, , and O  SO2  Cl O O Cl O H O H H H  O H  O S O Cl  Cl H Cl H H H H 328 • Chapter 18 ENOLS, ENOLATES, AND THE ALDOL CONDENSATION:
, -UNSATURATED ALDEHYDES AND KETONES 33. (a) (b) 3-Pentanone  H2CPCHCH3 (c) (d) 3-Pentanone  H2CPC(CH3)2 (b) and (d) show the results of E2 elimination: Alkylation requires an SN2 process and you already know that these are poor with secondary and impossible with tertiary haloalkanes. CH2CH(CH3)2 O CH2CH3 O 34. Both are aldehyde n enamine n alkylation sequences. The new carbon–carbon bond is marked with an arrow. (a) (b) CH2 CHCHO (via CH2 Br CH  CH N SN2 reaction) (CH3)2C CHCH2 CH2CHO via CH2 CH N 1559T_ch18_323-343 11/3/05 11:12 Page 328