1559T_ch18_323-34311/03/0522:01Pa9e336 EQA 336.Chapter 18 ENOLS,ENOLATES,AND THE ALDOL CONDENSATION:B-UNSATURATED ALDEHYDES AND KETONES aldehydes or ketones.New bond(s d CH-CHz -CH,CCH CH:CH (e)Intramolecular aldol condensations.leading to CH from (c)and OH from (d) CH-CH ⊕ 50. followed by aldol Ca-2 Heating in (a)and (b)tends to drive dehydration to give the B-unsaturated ketone produc 49. Michael additions: 1,4-additions of enolate ions to
, -unsaturated aldehydes or ketones. New bond(s) indicated by arrow(s). (a) (b) (c) (d) (e) Intramolecular aldol condensations, leading to from (c) and from (d) 50. Robinson annulation sequences (Michael addition followed by aldol). (a) (b) (c) (d) Heating in (a) and (b) tends to drive dehydration to give the
, -unsaturated ketone product. O O O  HC C CCH3 CH3 O Proton transfer O CH2 O product O OH O CH3 CH3 O H3C H3C CH3 CH3 O OH O OH CH CH2 CH2CCH3 CH3 CH3 CH3 CH3 O O C CH2CH2CCH3 CH CH2 O O CH2CH CH3 CH3 O O C C6H5CCH2 CH2CH2CC6H5 O O 336 • Chapter 18 ENOLS, ENOLATES, AND THE ALDOL CONDENSATION:
, -UNSATURATED ALDEHYDES AND KETONES 1559T_ch18_323-343 11/03/05 22:01 Page 336