Borane-1,4-Oxathiane

The conformations of isomers of 2,6-dichloro-l,4-oxathian have been determined from C—H spin-spin coupling constants.When 6-methyl-1,4-oxathian-2-one was ethylated, equal amounts of cis- and trart5-4-ethyl-6-methyl-2-oxo-l,4-oxathianium salts were formed. Several related compounds were synthesized, and their stereochemistry was studied.A new hydroborating agent, borane-oxathian (309), has several advantages over others for example, it is stable, moderately soluble in water, and has less odour than others. Its... 

Hydroboration. This complex of borane is more reactive than borane-dimethyl sulfide (4, 124, 191 5, 47) and has the added advantage that after hydroboration, 1,4-oxathiane can be removed easily as the water-soluble sulfoxide. 

HYDROBORATION Bis[3-methyl-2-buiyl] borane. 9-Borabicyclo[3.3.1 ]-nonane. Borane-l,4-oxathiane. Tliexyl-borane. 

Double bonds are converted to monohydroxy derivatives by acid catalyzed addition of carboxylic acids, followed by hydrolysis. The carbocation intermediate is prone to rearrangement, leading to a mixture of positional isomers. Hydroboration with borane l,4-oxathiane followed by aUcahne hydrolysis a regioselective reaction (62) has been used to prepare hydroxy fatty acids as GC-MS standards in high yield (63). 

Hydroboration.—Borane-l,4-oxathiane (1) is a convenient hydroborating agent with reaction characteristics similar to those of borane-tetrahydrofuran (BHj.THF) or borane-dimethyl sulphide (BMS). Like BMS, but unlike BH3.THF, it can be handled as a neat, stable material and can be utilized in a variety of solvents. Its odour is less unpleasant than that of BMS, and the oxathiane can be removed from many organic solvents by washing with water, particularly if it is first oxidized by means of hypochlorite solution. Hence,... 

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