Stephens coupling

Aryl-acetylene synthesis, Cf. Cadiot-Chodkiewicz coupling. 

An alternative mechanism similar to that of the Cadiot-Chodkiewicz coupling  

Direct amination of pyridines, quinolines, and other TV-heterocycles using sodium amide in liquid ammonia. 

Condensation of aldehydes with ammonia to afford pyridines. 

Kawata, T. Harano, K. Taguchi, T. Chem. Pharm. Bull. 1973,21, 604. 

Aryl-acetylene synthesis, Cf Cadiot-Chodkiewicz coupling and Sonogashira coupling. The Castro-Stephens coupling uses stoichiometric copper, whereas the Sonogashira variant uses eatalytie palladium and copper. 

1 copper acetyllde 2 sp halide DMF, base, A 3 disubstituted alkyne 

Example 1, A variant, also known as the Rosenmund-von Braun synthesis of aryl nitriles  

Bakunova, A. Bakunov, S. Wenzler, T. Barszcz, T. Werbovetz, K. Burn, R. Hall, 

Castro, C. E. Stephens, R. D. J. Org. Chem. 1963, 28, 2163. Castro and Stephens were in the Department of Nematology and Chemistry at University of California, Riverside. 

Stereoselective reduction of acetylenic alcohols to it-allylic alcohols using sodium bis(2-methoxyethoxy)aluminum hydride (SMEAH, also known as Red-Al) or Li-AIH4. 

1 copper acelylide 2 sp halide DMF, base, A 3 dlsubstituted alkyne R = alkyl or aryl r2 = gryi, vinyl, X = I, Br 

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 53, Springer International Publishing Switzerland 2014 

Name Reactions, 41h ed., DOI 10.1007/978-3-642-01053-8 47, Springer-Verlag Berlin Heidelberg 2009 

The reaction is believed to proceed via a four-centered transition state. 

In the laboratory of M. Nilsson, a facile one-pot synthesis of isocumestans (6H-benzofuro[2,3-c][1]benzopyran-6-ones) was developed via a novel extension of the Castro-Stephens coupling utilizing ortho-iodophenols and ethyl propiolate. The reaction can be regarded as an extended Castro-Stephens coupling where an intermediate cuprated benzofuran couples with a second equivalent of ortho-iodophenol, and the product lactonizes to isocumestan. 

Coleman and co-workers have developed a stereoselective synthesis of the 12-membered diene and triene lactones characteristic of the antitumor agent oximidines I and II, based on an intramolecular Castm-Stephens coupling. The effectiveness of this protocol rivals the efficiency of standard macrolactonization. The stereoselective reduction of the internai alkyne afforded the 12-membered ( ,Z)-diene lactone in good yield. 

During the total synthesis of epothilone B, J.D. White et al. used the modified Castro-Stephens reaction instead of a Wittig reaction for the coupling of two important subunits (A B) to avoid strongly basic conditions. 

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Castro-Stephens coupling"), which here exclusively involves rr Cu A, — rY ... 

The Castro-Stephens coupling also involves the reaction of copper(I) acetylide with aryl halides to form diarylacetylenes. 

This reaction is related to the Castro-Stephens Coupling. 

This reaction is closely related to the Sonogashira Coupling, which uses a catalytic amount of palladium and copper, whereas the Castro-Stephens coupling uses a stoichiometric amount of copper. 

Other references related to the Castro-Stephens coupling are cited in the literature. ... 

Gray, D. L. Castro-Stephens coupling. In Name Reactions for Homologations-Part 1 Li, J. J., Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2009, pp 212-235. (Review). 

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