Grignard anomalous

In some instances the reactions of the indole Grignard reagents resemble those of simple aryl or alkyl magnesium halides, but in many eases they appear to reaet anomalously. 

Example Sometimes copper solves other regioselecL-ivity problems. Addition of aryl Grignard (28) to enone (29) gives the anomalous product (30) in which the electrophile (29) has been attacked at the right atom but the nucleophile (23, arrows) has attacked with the wrong atom. 

The reaction of azirines with Grignard reagents is an anomalous reaction of imines. Normally an a-hydrogen is abstracted to give the enamine anion which is unreactive toward further attack of the Grignard reagent.64 The enamine derived from a 1-azirine is a 2-azirine (146) it is an unknown and probably unstable compound (Section I,A). 

Anomalous Grignard reactions (MeMgl) with esters of the 4,5-epoxy-6/3-hydroxycholestanes (617) and (618) lead to methylation at -6 rather than at C-4. The reactions are interpreted as rearrangements leading to 6-oxo-com-pounds, which then react rapidly with the Grignard reagent. In either the cis- or the trans-compound, the favourable migration of 6a-H to the 5a-position is a key... 

Anomalous Grignard reactions of 4,5-epoxy-6P-hydroxy-cholestanes Scheme 24... 

The C-4 reactivity of quinazoline, which is responsible for the anomalous basicity (see p 434), applies to other nucleophiles, e.g. the addition of Grignard compounds, enolates, cyanide or hydrogensulfite ... 

Phenylmagnesium iodide Dimerization with decarhalkoxylation Anomalous Grignard reaction... 

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