15597ch12220-24611/02/0521:55Pag0231 Solutions to Problems31 CH、H racemic CH:CHOHCHOHCH (别) Anti is also readily achieved. CHs 器a4 H+.H0 meso-chachoHcHOHCHa with inversion) (d)Need different reactions oneac ouble bond.Hydroboration is very selective for unhindered (CH3)2C=CHCH2CH2CH=CH2- -(CH3)2C=CHCH2CH2CH2CH2OH MCPBA CH:C2 CHC-CHCH.CH.CH.CH.OH .C.CH).CCHCH.CH.CH.CH 39.Starting compound is CH2=C(CH)CH,CH2CHs (a)(CH)zCHCH.CH.CH, (b)CH2DCD(CH,)CH.CH.CH (e)HOCH2CH(CH,)CH2CH2CH, (d)(CH),CCICH,CH,CH, (e)(CHs)2CBrCH2CH:CHs (f)BrCH2CH(CH,)CH2CH2CH (g)(CH3CICH.CH.CH (h),(p)(CH3)C(OH)CHCHCH (peroxides don't affect HI addition) O CICH-CCICH CH-CH-CH (D ICH-CCICHCH-CH CH (k)BrCH-C(OCH CH(CH3CHCH CH ()CHaSCH2CH(CH,)CH.CH.CH, (m) aloaataat (n)HOCH2C(OHX(CH)CH2CH2CH (o)H2C-O+CH3CCH-CH2CH3 (Q)(CH)2C=CHCH2CH:Solutions to Problems • 231 (b), (c) Because dehydration gives mainly trans alkenes, these problems involve finding ways to add two OH’s either anti (88n meso) or syn (88n racemic). Syn is easy. Anti is also readily achieved. (d) Need different reactions on each double bond. Hydroboration is very selective for unhindered double bonds, so a primary alcohol is easy to make. Then MCPBA can form an oxacyclopropane at the trisubstituted double bond. Finally, oxidation to an aldehyde finishes the synthesis. 39. Starting compound is CH2PC(CH3)CH2CH2CH3. (a) (CH3)2CHCH2CH2CH3 (b) CH2DCD(CH3)CH2CH2CH3 (c) HOCH2CH(CH3)CH2CH2CH3 (d) (CH3)2CClCH2CH2CH3 (e) (CH3)2CBrCH2CH2CH3 (f ) BrCH2CH(CH3)CH2CH2CH3 (g) (CH3)2CICH2CH2CH3 (h), (p) (CH3)2C(OH)CH2CH2CH3 (peroxides don’t affect HI addition) (i) ClCH2CCl(CH3)CH2CH2CH3 (j) ICH2CCl(CH3)CH2CH2CH3 (k) BrCH2C(OCH2CH3)(CH3)CH2CH2CH3 (l) CH3SCH2CH(CH3)CH2CH2CH3 (m) (n) HOCH2C(OH)(CH3)CH2CH2CH3 O B (o) H2CPOCH3CCH2CH2CH3 (q) (CH3)2CPCHCH2CH3 CH2 C(CH3)CH2CH2CH3 O CHCH2CH2CH (CH3)2C CHCH2CH2CH2CH2OH (CH3)2C CH2 MCPBA CH2Cl2 1. BH3, THF 2. H2O2, HO (CH3)2C CHCH2CH2CH2CH2OH PCC, CH2Cl2 (CH3)2C CHCH2CH2CH2CH O O O meso-CH3CHOHCHOHCH3 CH3CO3H CH2Cl2 H, H2O (with inversion) CH3 H C C CH3 O H CH3 C C CH3 H H racemic CH3CHOHCHOHCH3 1. OsO4, THF 2. H2S (syn) CH3CHOHCH2CH3 H2SO4,  CH3 C C CH3 H H 1559T_ch12_220-246 11/02/05 21:55 Page 231