Retro Favorsky Reaction

Terminal acetylene by potassium-bydroxide-catalyzed retro-Favorsky reaction [160b] [Eq. (39)]... 

TABLE XXn. Ethynyl- and Polyethynylpyrazoles Prepared by Retro-Favorsky Reaction [69IZV2546 69KGS1055 71IZV1764 72IZV2524 86TH1 88M253]. 

Tertiary acetylenic alcohols or their ether derivatives may be usefully exploited in both Castro and Cadiot-Chodkiewicz reactions. In these cases, base-catalyzed retro-Favorsky reactions can be employed to liberate the required terminal acetylenes from the alcohol products [16]. A concise account of Chodkiewicz s contributions to this method are given elsewhere (ref. 9b, pp. 622-3). Further examples are shown in Fig. 1.11. 

CMejOH stable stable stable use Thp ether stable may be removed by retro-Favorsky reaction. (use K2CO3)... 

Additional examples of the Sonogashira reactions of pyridine triflates include coupling of 2-pyridyltriflate and 3-hydroxy-3-methylbut-l-yne to afford alkyne 141 [114], The carbinol adduct could be readily unmasked to give 2-ethynylpyridine via a basic-catalyzed retro-Favorsky elimination of acetone. Due to the volatility of 2-ethynylpyridine, use of a high boiling liquid such as paraffin oil for the basic hydrolysis made the distillation more convenient [115]. 

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