1559r_eh25.439-45310/20/055:59 AM Page448 448.chapter 25 HETEROCYCLES:HETEROATOMS IN CYCLC ORGANIC COMPOUNDS 42.Reaction with an activated derivative of acetic acid such as the anhydride would provide the product 0位 -6.c 43.(a)CoH CH:CH,-C.H CH- 44.(a)1.3-Dibromo-5.5-dimethyl-1.3-diaza-2.4-cyclopentanedione (b)Thinking mechanistically,you have the following: c电q电2Hau CH:CHs Br (CH:)C -C(CH3)2- CH)-CCHh一 OOH HO-O (CHC-CCH)() 0-0 yclabute 45.Abbreviated mechanism (note the"double"Michael addition). (CH)C-CHCCH-CCH)NH (CH)CCHCCH.CICH) 一NH242. Reaction with an activated derivative of acetic acid such as the anhydride would provide the product. 43. (a) (b) 44. (a) 1,3-Dibromo-5,5-dimethyl-1,3-diaza-2,4-cyclopentanedione. (b) Thinking mechanistically, you have the following: 45. Abbreviated mechanism (note the “double” Michael addition). CHCCH O (CH3)2C C(CH3)2  NH3 1,4-Addition CHCCH2C(CH3)2 O NH2 (CH3)2C Again product H (CH3)2C O O C(CH3)2 (CH3)2C O O C(CH3)2 H  ii 3,3,4,4-Tetramethyl- 1,2-dioxacyclobutane Ag AgBr (CH3)2C Br OOH C(CH3)2 (CH3)2C HO O C(CH3)2  i CH3 CH3 CH3 CH3 C C CH3 CH3 C CH3 CH3 C Br  “Br HOOH ” C6H5CH NC6H5 ClCHCOOCH2CH3 C6H5CH C6H5N  Cl CHCOOCH2CH3 Cl  product  C6H5CH O C6H5CCOOCH2CH3 Cl C6H5CH C6H5  O Cl CCOOCH2CH3 Cl  product  Further H2O NH2 CH3 NH2 O O O CH3 CH3COOH NH2 CH3  product C C Make amide first C O H N  448 • Chapter 25 HETEROCYCLES: HETEROATOMS IN CYCLIC ORGANIC COMPOUNDS 1559T_ch25_439-453 10/20/05 5:59 AM Page 448