Propinoic acid

By the oxidation of propargyl alcohol, propinol, CH=C—CH2OH (p. 167), an acid is obtained having the constitution CH=C—COOH and known as propiolic acid or propinoic acid and also as acetylene carboxylic acid. This is the simplest acid of the ethine series and the only one we shall mention. Derivatives of it are of importance in the benzene series in Part li as will be shown later. 

In order to probe the tolerance of the molybdenum(O) aromatic complexes to electrophilic/acidic environments, a tandem addition sequence was attempted for the complex TpMo(NO)(MeIm)(q -naphthalene) (114) (Fig.25) [17]. In a strategy similar to that used with the TpRe(CO)(MeIm)(q -naphthalene) analog,(see below) an acetonitrile solution (-35 °C) of 114 was exposed sequentially to triflic acid, l-methoxy-2-methyl-l-trimethylsiloxypropene, and an amine base. The 1,2-dihydronaphthalene complex 116 was isolated in virtually quantitative yield. No evidence of free naphthalene or 1,4-addition product was observed. Stirring the reaction mixture with exposure to air resulted in an 80% overall yield of 2-(l,2-dihydro-naphthalen-2-yl)-2-methyl-propinoic acid methyl ester (117) following TLC purification [17]. 

The p-carboline alkaloids are heterocyclic amines, biosynthesized from combination of five- and six-ringed (i.e., cyclic) carbon structures, containing an amine group, p-carboline is made up of planar tricyclic ring structures derived from L-tryptophan (i.e., a-aminoindole-3-propinoic acid), a neutral heterocyclic amino acid containing essentially an indole ring system. The shikimic acid... 

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