Eliminations alkynes

The phosphonite 81 was shown to render a phosphonium salt 84 by interaction with the primarily obtained N-acyliminium salt 83. Deprotonation transformed 84 to the oxaphosphohdine 85, which undergoes l,3-dipolar cycloaddition with the activated alkyne elimination of phosphonate from the adduct 86 gives rise to the pyrrole system 82. In contrast to Mtinchnones (cf. p. 175), the mesoionic 1,3-dipoles of type 85 show high regioselectivity in the cycloaddition process. 

Naming Alkynes Preparation of Alkynes Elimination Reactions of Dihalides... 

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