Details

Autor(en) / Beteiligte

• Basil J. Wakefield

Titel

5 - Addition of Organomagnesium Compounds to Carbon-Nitrogen Multiple Bonds

Ist Teil von

• Organomagnesium Methods in Organic Chemistry, 1995, p.87-109

Ort / Verlag

Academic Press

Erscheinungsjahr

1995

Link zum Volltext

Quelle

ScienceDirect eBooks

Beschreibungen/Notizen

• This chapter describes the addition of organomagnesium compounds to carbon–nitrogen multiple bonds. Unconjugated carbon–nitrogen double bonds are less reactive than what was originally predicted for the addition of organomagnesium compounds. When imines possess hydrogen atoms α to carbon or nitrogen, deprotonation may compete with addition. Imines may be activated by complexation with Lewis acids, but this also increases the acidity of α-hydrogen atoms. A combination of copper halide and boron trifluoride etherate is a possible solution to the problem. It is noted that in cases where the stereochemistry of the addition is dependent on chelation control, the presence of Lewis acids may profoundly influence the selectivity. Analogous reactions with ketonitrones proceed less readily, and are more liable to side-reactions involving deprotonation, but may give good results under optimized conditions. The addition may proceed with a useful degree of stereoselectivity. The initial adducts may be readily converted into amines or by reaction with carbon disulfide. Primary amines have been prepared through addition of Grignard reagents to various N-metalloaldimines, followed by hydrolysis. Conjugated addition is the first step in Meyers' strategy for multiple carbon–carbon bond formation.