Iron-Catalyzed Cadiot–Chodkiewicz Coupling with High Selectivity in Water under Air

Abstract

An iron-based catalytic system was developed for the cross-coupling of 1-bromoalkynes with terminal alkynes to selectively generate unsymmetrical 1,3-butadiynes in water under air. It was found that a combination of 1-bromoalkynes derived from less acidic terminal alkynes with more acidic counterparts would greatly enhance yields and selectivity for unsymmetrical 1,3butadiynes. The reaction was also applicable for the synthesis of unsymmetrical 1,3,5-hexatriynes through coupling of 1-bromoalkynes and trimethylsilyl-protected 1,3-butadiynes in a one-pot manner.

Air Tolerant Cadiot–Chodkiewicz and Sonogashira Cross-Couplings

“…A similar method has also been developed for high-yield Sonogashira cross-couplings, raising the prospect of extension to other Pd(0)-catalyzed processes. The convenience offered by this protocol compares favorably with other recently reported optimizations − and augurs well for its widespread use.…”

Rhodium-catalysed homo-coupling of terminal alkynes: divergent synthesis of bioactive 1,3-diynes and conjugated enediynes

“…4 In the past few decades, significant efforts have been made to synthesize 1,3-diynes including the classic homo-coupling of terminal alkynes such as Glaser, 5 Eglinton, 6 and Hay, 7 coupling reactions which provide straightforward access to the symmetrical product (Scheme 1a). The Cadiot–Chodkiewicz coupling reaction 8 represented another typical protocol for preparing unsymmetrical 1,3-diynes by hetero-coupling between a terminal alkyne and a haloalkyne (Scheme 1b). However, some drawbacks are often unavoidable in these protocols such as the undesired halogen-metal exchange reactions, 7 complex reaction conditions, 9 poor selectivity, 10 etc.…”

Highly Efficient Conversion of Homocoupling and Heterocoupling of Terminal Alkynes Catalyzed by AuCu24/AC‐200

“…[1][2][3] In recent years, the synthesis of symmetric and asymmetric 1,3-diynes have been widely concerned. [4][5][6][7] Great progress has been made in obtaining highly active 1,3diynes reactions with copper based catalyst systems. [8][9][10][11][12][13] An unsaturated coordination N-doped copper oxide (N-CuO x ) heterogeneous catalyst has been synthesized by Ke and coworkers, [14] which has good catalytic performance in direct oxidative coupling of alkynes without addition at 80 °C.…”

“…Conjugated 1,3‐diynes are widely used in drug synthesis and the preparation of some organic materials, and also exist in natural products [1–3] . In recent years, the synthesis of symmetric and asymmetric 1,3‐diynes have been widely concerned [4–7] . Great progress has been made in obtaining highly active 1,3‐diynes reactions with copper based catalyst systems [8–13] .…”