Mercury compounds sulfoxides

Oxidation of the sulfur- or selenium-bridged azepines (171 X=S or Se) with mercury(II) oxide in methanol yields ultimately the 4f/-azepine (68JCS(C)23ll) with hydrogen peroxide as oxidant, the sulfur compound furnishes the sulfoxide (171 X=SO). Selenium dioxide oxidation of 7,8-dimethyl-lf/-l-benzazepin-2-one affords the 2,3-dioxo derivative (173) that displays no evidence of enol tautomers or heteroaromaticity (7ici(L)1439). 

The hexasolvated compound was being prepared from a mixture of the hydrated salt, methanol and dimethyl sulfoxide but inexplicably mercury(I) oxide came out of solution. This was redissolved by addition of perchloric acid and the solution was refrigerated for 60 h. After addition of molecular sieve to remove the water present, the solution was filtered and the sieve treatment repeated four more times. During the final filtration, a violent explosion occurred in the funnel. The most likely cause was formation of methyl perchlorate promoted by the dehydrating action of the sieve, but dimethyl sulfoxide also forms an unstable salt with perchloric acid, so this also may have been involved [1], During preparation of... 

In contrast, the latter. ryw-isomer, ethyl (TS,2R)-2-(1 -hydroxymethyl)-4-pentenoate. was recently prepared as the only product of a reduction with an enzyme fraction obtained from baker s yeast176. Introduction of a sulfur-containing functional group into the substrate increases stereocontrol in baker s yeast reduction of many ketonesI2e>. 2-Methylthio-3-keto esters are selectively reduced to the (3S)-3-hydroxy esters (Table 5)123,127. The 2-methylthio group is easily removed by 3-chloroperbenzoic acid oxidation to the corresponding sulfoxide followed by subsequent reduction with aluminum-mercury amalgam. Thus, these compounds can also be used for the preparation of optically pure 2-unsubstituted 3-hydroxy esters. 

Coordination of mercurial species is certainly involved in several of these processes. Although the strictly inorganic compounds of mercury form well-defined coordination complexes with amines, phosphines, sulfoxides, phosphine oxides, and amine oxides, particularly when a noncoordinating gegenion for mercury is employed, coordination numbers up to six having been observed (56), the coordination chemistry of organometallic derivatives of mercury is just developing (87-89). 

---