Grignard reactions, copper-catalysed

Gigg and Conant [47] have described the synthesis of the oxirane (49) as an intermediate for the synthesis of the protected sphingosine derivative (52). The oxazoline (1) was converted into the allyl furanoside (cf. 2) which gave the oxirane (49). The copper-catalysed Grignard reaction on (49) should give (50) which can be converted... 

The use of the o-diphenylphosphanylbenzoyl leaving group in copper-catalysed allylic substitution reactions with a Grignard reagent has been studied extensively.7 ( ) High SN2 regiospecificity (>95%) and complete stereospecificity are observed at room temperature when the solvent is a dichloromethane - diethyl ethyl mixture. 

Corey chose a Wittig-style (HWE) reaction to control the aldol process and copper-catalysed addition of vinyl Grignard for the conjugate addition. Oxidation with NaI04 and catalytic OSO4 gave the keto-aldehyde 35 which cyclised cleanly under equilibrating conditions. 

Reactions of organomagnesium compounds with dialkyl sulfates or alkyl sulfonates often give satisfactory yields of the products of displacement of sulfate or sulfonate. Side-reactions have been observed, but they can often be avoided for example, an excess of the sulfate or sulfonate should be used with Grignard reagents, as some is consumed by nucleophilic attack by halide ion [A]. The dialkyl sulfates are reactive, but hazardous. Toluenesulfonates (tosylates) are less reactive, but their reactions are catalysed by copper complexes the reactions of trifluoromethanesulfonates (triflates) are catalysed by nickel complexes. Reactions of Grignard reagents with secondary tosylates appear to follow an Sn2 mechanism, with inversion of configuration [43],... 

Indolyl A-Grignards, "" or even better their zinc analogues, undergo reaction predominantly at C-3 with a variety of carbon electrophiles such as aldehydes, ketones and acid halides, or reactive halo-hetero-cycles. Including aluminium chloride in the zinc reactions produces high yields of 3-acyl-indoles. The copper-catalysed reactions of indolyl-A-Grignards with A-t-butoxycarbonyl-aziridines also proceed well at C-3. ... 

Synthesis of dideuteriomethylene hydrocarbons by copper catalysed reaction of Grignard reagents... 

Isopropylidene alkylidenemalonates undergo copper-catalysed conjugate addition with Grignard reagents yields of between 80 and 86% are reported for seven examples. Direct lithiation of the acrylic acid derivative (10), followed by reaction with COg, gives the oxaloacetic acid monoester (11) (Scheme 8). ... 

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