Hemi-orthothiol esters

Halogenation of ketones, 275 Hemi-orthoester, 63 Hemi-orthoamide, 103-105 Hemi-orthothioamide, 144 Hemi-orthothiol esters, 93-97 Hinesol, 250... 

Kaloustian and Khouri (73-76) have studied the cleavage of hemi-orthothiol ester tetrahedral intermediates generated by the reaction of dialkoxycarbon-ium ions with hydrosulfide anion in aprotic solvent. The results obtained show that cleavage of the hemi-orthothiol ester intermediate is subject to stereoelectronic control. 

The authors (73) have first observed that cyclic dialkoxycarbonium ions 153 and 154 (RsCHj or CgHg) as well as acyclic dialkoxycarbonium ion 155 (R=CH3 or CgHg) reacted with sodium hydrosulfide (NaSH) to give monothioesters 159 and 160 and thionobenzoate 161 respectively. These results show that the hemi-orthothiol esters 156, 157, 158 must be formed as intermediates in these reactions. The salts 153 and 154 (R=H) behave in a similar fashion (nmr and tic analyses), but isolation of the products (159 and 160, (R=H)) was thwarted by their high reactivity. 

Kaloustian and Khouri (74) have also observed that the sodium salts 174 (n = 2 and 3) of the hemi-orthothiol esters 156 and 157 are stable tetrahedral intermediates. These insoluble salts were produced by reacting the... 

The cleavage of a hemi-orthothiol ester, formed from the combination of a hydrosulfide ion with a dialkoxycarbocation, was found to occur under stereo-electronic control. The cyclic dialkoxycarbocations 137, Eq. 36, and 140, Eq. 37, and the acyclic dialkoxycarbocation 143, Eq. 38, were reacted with sodium hydrosulfide to give the monothioesters 139 and 142, and the thionobenzoate 145, respectively [11-13]. 

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