Reported herein is the first example of a gold-catalyzed cyclization of bis­(arylmethyl)­ethynylphosphine oxides. This represents an original approach to bridgehead methanophosphocines 1, eight-membered heterocycles. Gold catalyst in combination with triflic acid activates alkyne and induces a double hydroarylation. Mechanistic studies suggest that the reaction proceeds stepwise, forming first the 1H-isophosphinoline 2-oxide 5. Reduction and protection of the corresponding phosphine oxides 1 described herein also highlight the effectiveness of our approach to this new class of electron-rich ligands.

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The synthesis of pseudodisaccharides based on an oxaphosphinane heterocycle is described. Disaccharide mimetics 5 and 6 were readily obtained through glycosylation of a hydroxy group with appropriately protected furanosyl or pyranosyl carbohydrates using a trichloroacetamidate coupling strategy. Selective or complete deprotection then produced the chiral pseudodisaccharides in good yields.