Abstract

Highly reactive 1 : 1 intermediates were produced in the reaction of Ph 3P and dialkyl acetylenedicarboxylates¼dialkyl but-2-ynedioates). Protonation of these intermediates by alcohols (2,2,2-¼ prop-2-yn-1-ol), MeOH, benzyl alcohol, and allyl alcohol¼ prop-2-en-1-ol) led to vinyltriphenylphosphonium salts 4, which underwent a Michael addition5 ( corresponding densely functionalized 2 structures of the final products were confirmed by IR, spectrometry. The configuration of dimethyl 8,8a-dihydro-8-oxo-8a-(2,2,2-trichloroethoxy)-2 2,1- establishing that the one-pot multicomponent condensation reaction was completely diastereoselective. Scheme). Wittig reaction of the stabilized phosphonium ylides with ninhydrin (6) led to theH-indeno[2,1-b]furans 10 in fairly good yields (Table 1). The1H- and 13C-NMR spectroscopy, and massH-indeno[b]furan-2,3-dicarboxylate (10a) was established by a single-crystal X-ray structure determination, ( trichloroethanol, propargyl alcohol ( ( reaction with the conjugate base to produce the corresponding stabilized phosphonium ylides