Diazo compounds, alkylation with sulfur

A -Unsubstituted 1,2,4-diazaphospholes (4) undergo A -alkylation by reaction with alkyl vinyl ether, sulfur ylides, and diazo compounds <95HAC403>. They react with acyl chlorides in a 2 1 molar ratio to give a mixture of the A -acylated diazaphosphole and the diazaphosphole hydrochloride. Preparative A -acyclation is achieved in presence of a tertiary amine. Sulfonyl chlorides and phosphorus trichloride also give A -substitution reactions (Scheme 2) <87TH 422-01 >. 

Nitro compounds are reduced to the corresponding amine. Unlike hydride reductions, both alkyl nitro compounds (2-methyl-2-nitro-1,3-propanediol was reduced to l-amino-2-methyl-1,3-propanediol in 95% yield)566 and aromatic nitro derivatives [nitrobenzene was reduced to aniline with Ti(S04)3 in sulfuric acid and cetyltrimethylammonium bromide] are electrolytically reduced. 7 jf conditions are modified, reductive coupling can give azoxy compounds such as 568 (from 569) or diazo compounds. A variety of acid derivatives are reduced under electrochemical conditions, including nitriles (to amines), acids (to alcohols),5 E572 estejs (jq alcohols), and amides (to alcohols). It is possible to selectively reduce a cyclic imide to a lactam.575... 

Sulfur ylides are useful reagents in organic synthesis. The ylide is formally a zwitterion in which a carbanion is stabilized by interaction with an adjacent sulfonium centre. They are usually prepared by proton abstraction from a sulfonium salt with a suitable base or by reaction of a sulfide with an alkylating agent such as Me30+BF4 or a carbene formed, for example, by metal-catalysed or photolytic decomposition of a diazo compound (1.103). 

---