Chlorohydrin acetates

The C = C bond in 3,3,3-trifluoro-2-methylprop-l-eneis readily oxidized in 76 % yield by bubbling the substrate into a cooled solution of hypochlorous acid (Table 6).98 Chlorohydrins together with 1,2-dichloro derivatives arc obtained by oxidation of alkenes with tert-butyl hypochlorite when the reaction is performed in acetic acid instead of water, chlorohydrin acetate is formed (Table 6)."... 

Dansette and Jerina25 found that cis- 1,2-glycols (34) on treatment with trimethyl orthoacetate in refluxing benzene containing a trace of benzoic acid are converted to an enantiomeric mixture of 2-methyl-2-methoxydioxolanes (orthoesters) (35 and 36). On reaction of this mixture with trimethylsilyl chloride, substitution with inversion takes place, and trans-chlorohydrin acetate (37) is formed. The chlorohydrin acetate is cyclized to an arene oxide on treatment with sodium methoxide. 

Chloramine T ((H ) is a powerful positive chlorine releasing reagent toward alkenes in acetic acid, giving mainly a ira/u-chlorohydrin acetate (73) as shown in Scheme 7. The similar reaction in an acetone/H20(l l)/H2S04 system under reflux produces chlorohydrins in moderate yields. - 7... 

Manganese (III) acetate or chloride salts [Mn30(0Ac) H0Ac, MnCb] can react with alkenes to afford 1,2-dichlorides and chlorohydrin acetates (equation 16). i The manganese(III) reagent promotes the chlorination of 1,6-heptadiene (42) to afford almost equal amount of open chain and cycliz dichlorides... 

Biscyclopentadienylyttrium chloride also promotes epoxide cleavage with acyl chlorides, giving chlorohydrin acetates. ... 

Starting from 2-ethylphenol 43, and after a five-step sequence, rac-44 was prepared with 42% yield. The DKR of this intermediate was carried out at 40°C for 24 hours, with chlorohydrin acetate (5)-45 being obtained in 96% yield with >99% ee. Further treatment of (S)-45 with LiOH in EtOH at room temperature led to enantiopure (R)-epoxide 46 (95% yield). Finally, the ring opening of 46 under optimized conditions with neat tcrt-butylamine overwhelmingly afforded the desired regioisomer (/f)-bufuralol (bufuralol/isobufiiralol 10 1) with >98% ee and 83% yield. 

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