Cadiot-Chodkiewicz-type coupling

Much of the new chemistry on the coupling of alkynyl halides has dealt mostly with applications of known methods. The Cadiot-Chodkiewicz-type coupling reactions (i.e. terminal acetylene coupling with alkynyl halides) have formed the cornerstone of synthesis of acetylenic retinoids (i.e. 9)58. 

Utesch, N. F., Diederich, F. Acetylenic scaffolding on solid support Poly(triacetylene)-derived oligomers by Sonogashira and Cadiot-Chodkiewicz-type cross-coupling reactions. Org. Biomol. Chem. 2003,1, 237-239. 

Ethynylcopper compounds, isolated or generated in situ, play a fundamental role in acetylene synthesis. The reactions basically are of three types the Glaser and Cadiot-Chodkiewicz oxidative couplings employed in polyacetylene synthesis, and the Castro coupling for preparing arylacetylenes (for comprehensive reviews of these reactions see ref. 9). 

The same authors prepared the Qo acetylenic cyclophanes detailed in Scheme 6.7, which possesses meta-substituted benzene rings at the core [16]. A Cadiot-Chodkiewicz type cross-coupling reaction of terminal acetylene 40 with dibromide... 

The conversion of the dehydrotrimer 135 into the corresponding bis-cuprate followed by coupling with dibromide 131 (Cadiot-Chodkiewicz conditions) gave the expanded [5]pericycline 122 in 53% isolated yield (Scheme 28) [4]. The more versatile approach by simple oxidative cyclooligomerization of dehydrooligomers of type 135 under high dilution conditions as shown in Scheme 28 provided the acetylene-expanded [3]- 82, [5]- 122 and [6]pericyclines 163 in reasonable to excellent yields [4,7]. 

Whereas Glaser-type oxidative coupling opens efficient synthetic pathways toward symmetrical diynes, its performance in heterocoupling is poor. The latter may be accomplished by Cadiot-Chodkiewicz coupling of terminal alkynes with 1-haloalkynes (usually 1-bromoalkynes). The reaction is conducted in the presence of an amine and catalytic amounts of a copper(I) salt. Because, in contrast with the Glaser-type reactions described above, it follows a nonoxidative reaction mechanism, oxygen is not necessary - but needs often not to be excluded (Scheme 4) [9]. 

The same type of reactions includes the Chodkiewicz-Cadiot reaction, i.e., a coupling of terminal acetylenes with bromoacetylenes, which is performed in... 

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