Résumé

Although a-lithio ylide Ph3P+C-HBr was generated from [Ph3PCH2Br]Br through halogen-metal exchange, the reaction of Ph3P+C-H2 with Me3CLi or Me2CHCH2Li produces the o-lithio ylide I nearly quant. I is stable at -60 Deg but slowly decomps. at higher temps. via a cyclization product II to give the a-lithio phosphole III, as shown by 1H NMR. [on SciFinder (R)]

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