No abstract

No abstract

of 195°( see Table I). The ir [3500 (OH), 1710 cm-' (C=0)] and nmr [ 3.43 (1, b, OH), 3.00 (1, m, -COCH<, 7 = 7 Hz), 1.27 (6, s, -C(OH)(CH3)2), 1.04 (6, d, -CH(CH3)2, 7 = 7 Hz] were in agreement with the values previously published.27 2-Acetoxy-2,4-dimethyl-3-pentanone (4-OAc). Keto ester 4-OAc was collected by preparative glpc using a column temperature of 195°( see Table I): ir 1744 and 1723 (0=0), 1252 cm-1; nmr 2.90 (1, h, -COCHC, 7=7 Hz), 2.01 (3, s, -02CCH3), 1.43 (6, s, -C(OCOCH3) (CHs)2), 1.03 (6, d, -C0CH(CH3)2, 7 = 7 Hz); mass spectrum m/e 172 [M]+, 129 [(CH3)2CHC0C(CH3)20]+ and/or [ 30 20( 3)20 ]+, 101 [CH3C02C(CH3)2]+, 71 [(CH3)2-]+, 59 [CH3C02]+, 43 [(CH3)2CH]+, and/or [CH3C=0]+. The ir and nmr values were in agreement with values previously reported in the literature.15b

on 10% (w/v) solutions in chloroform-d-carbon disulfide (1 : 1, v/v)11 with tetramethylsilane (7 10.00) as internal standard.trans-Hexahydro-1,3,S-benimtrioxepane (2) and rruns-syn-truns-4,s: 9,10-biscyclohexano-1,3,6,8-tetraoxacyclodecane (3) were prepared according to the procedure of Brimacombe, et a/. ' The trioxepane 2 had bp 34-37" (0.02 mm) and n M D 1.4659 (1it.l nl'D 1.4657). The tetraoxacyclodecane 3 had mp 164.5-165.5' (lit. mp 166-167.5').(11) This mixed solvent system was used because it was suitable for low-temperature studies, which will be reported elsewhere at a later date. meso-(4) and dl-di-(rruns-2-hydroxycyclohexyloxy)methane (5) were prepared according to the procedure described by Head.6The meso compound 4 had mp 80-82" ( l k 6 mp 81-82") and the dl modification 5 had mp 102.5-103.5" (lit.6 mp 104-105"). Abstract:The pure geometric isomers of l-benzyl-l,3-dimethylphospholanium bromide (la and lb) have been prepared and were subjected to treatment with aqueous sodium hydroxide. This resulted in the formation of the isomeric 1,3-dirnethylphospholane 1-oxides (2a and 2b) with complete retention of configuration. Arguments are presented favoring a stereospecific apical-equatorial displacement reaction. Reaction of la and lb with sodium n-butoxide gave 2a and 2b with a high degree of retention but with detectable inversion. The pure oxides (2a and 2b) yielded identical mixtures of these oxides when treated separately with concentrated hydrochloric acid. Pseudorotation of an intermediate phosphorane is suggested as being responsible for the formation of product mixtures. The oxide 2b was observed to be reduced smoothly by phenylsilane to the corresponding phosphine (4b) with complete retention of configuration. Phosphines 4a and 4b are configurationally stable for long periods at 150'. Unlike 1, 1 ,I-dimethylphospholanium bromide (22a) underwent slow cleavage with aqueous sodium hydroxide forming ring-opened product (23) as well as manifesting cleavage external to the ring (22b). n a preliminary communication,2 it was reported

diglyme for 1 hr. GLC analysis (SE-30) indicated a 95% yield of V. The product was isolated by distillation: bp 74°(5 mmHg) [lit. bp 121°(30 mmHg)];23 NMR (CDC1S) 5 1.6 (m, broad, 6, aliphatic), 3.6 (m, broad, 4, -CH2O and CH2CI), 3.9 (s, 1, OH).Acknowledgment. We wish to thank the Research Corporation for support of this study.