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Development of a cost efficient and scaleable process for 2-quinoxalinecarboxylic acid is described. The primarily goals of the development work were to improve the overall yield of the process, to minimize the use of environmentally unacceptable materials, and to obtain a material with a high level of purity. A variety of approaches were examined, and the most efficient method was a condensation of o-phenylenediamine with a monosaccharide followed by a mild peroxide oxidation.

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Palladium-Catalyzed Additions of Terminal Alkynes to AcceptorAlkynes.-In the presence of a catalytic amount of Pd(O-Ac)2 and an electron-rich sterically encumbered ligand such as P(Dmp)3 the C-H bond of a terminal alkyne can be added to either terminal alkynes (self-coupling) or activated internal alkynes (cross-coupling) as is demonstrated for the examples (II) and (V). The internal alkynes bear functional groups such as ester, sulfone and ketone. In these reactions also 1:2 adducts can be obtained. Product (VII) serves as useful precursor to β-keto esters. Application of this method is shown in an iterative sequence starting from (IX) to produce the novel conformationally rigid retinoid analogue (XII). -(TROST, B. M.; SORUM, M. T.; CHAN, C.; HARMS, A. E.; RUEHTER, G.; J. Am. Chem. Soc. 119 (1997) 4, 698-708; Dep. Chem., Stanford Univ., Stanford, CA 94305, USA; EN)