Carbonyl tosylhydrazone reductive deoxygenation

R. O. Hutchins and N. R. Natale. Sodium borohydride in acetic acid. A convenient system for the reductive deoxygenation of carbonyl tosylhydrazones. J. Org. Ghent., 1978, 43, 2299. 

Deoxygenation of carbonyl compounds (6, 98 7, 54 8, 79-80). This easily prepared borane is as effective as catechol borane for reduction of tosylhydrazones of carbonyl compounds to the corresponding methylene compounds. 

A milder approach for the deoxygenation of aldehydes and ketones involves treatment of the preformed hydrazone with t-BuO K in DMSO at room temperature. Alternatively, conversion of the carbonyl group of aldehydes and ketones into the corresponding tosylhydrazone and reduction of these with NaBH3CN ° or with (RC02)2BH produces the desired methylene compounds in good yields. 

In situ reduction of tosylhydrazones by NaBHjCN provides an efficient method for the deoxygenation of carbonyl compounds to furnish the corresponding hydrocarbons (see also Section 3.4). In the case of tosylhydrazones derived from a,P-unsaturated carbonyl compounds, the reduction leads to a stereoselective migration of the double bond to give the corresponding tran -alkene. 

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