Homer-Wittig reagents

This Wittig-Homer reagent is prepared from 0,N-dimethylhydroxylamine and chloroacetyl chloride and N(C2H5)3 in CH2C12 followed by reaction with triethyl-phosphite. The anion (BuLi) of 1 reacts with aldehydes or ketones to form hydrox-lmates, which are reduced to aldehydes by LiAlH4 (11, 201-202).1... 

J. Seyden-Penne, Lithium Ccoordination by Wittig-Homer Reagents Formed by a-Carbonyl Substituted Phosphonates and Phosphine Oxide, Bull. Soc. Chim. Fr. 1988, 238. 

Enamines.1 This Wittig-Homer reagent (1) is not useful for reactions with ketones because of its basicity. This difficulty is overcome by use of (N-methylani-lino)methyldiphenylphosphine oxide (2), which undergoes Wittig-Homer reactions with a wide variety of ketones as well as aldehydes to give N-methylanilino enamines (3) as a mixture of (E)- and (Z)-isomers. The less stable (Z)-isomers can be isolated by crystallization at low temperature. 

They also reported the synthesis of the ( )-11,12,14,15-bis-dehydro-LTA4 (37) from reacting the same phosphonate Wittig-Homer reagent (38) with ( )-6-formyl-5,6-epoxyhexanoate (Scheme 5.12). 

The following example (Scheme 15) is representative, as preparation of the Wittig-Homer reagent... 

When a 2-thiomethyl-l,3-selenothiolium iodide such as (84) reacts with an aryl ketone (85) in pyridine-acetic acid, fulvenes such as (86) are obtained reaction with a Wittig-Homer reagent takes place at both carbonyl groups (Equation (8)) <90PAC473,91JCS(Pl)157>. 

Ketophosphonates. These useful Wittig-Homer reagents are easily pre> pared by reaction of an s-lithiophosphonate (a) with Cul or CuBr to form an organocopper derivative (b), which reacts readily with an acid chloride to form / -ketophosphonate (2). 

A second route to epoxides of type 651 can evolve from treatment of the fluorinated Wittig Homer reagent 652 with aldehydes or ketones [253]. 

Wittig-Homer reagents, such as those of Scheme 3.8, with ketones (compounds of Table 3.2) are used for preparation of extended 7i-donor molecules. In... 

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