Phosphonium salts and phosphoranes. Part 5. Thermal and electron-impact induced fragmentation of heteroaroylmethylenetriphenylphosphoranes.

One‐Shot Double Elimination Process: A Practical and Concise Protocol for Diaryl Acetylenes

“…37 :18 M.p. : 48–50 °C; 1 H NMR (300 MHz, CDC1 3 ): δ =7.01 (dd, J =5.0, 3.5 Hz, 1 H), 7.27–7.30 (m, 2 H), 7.33–7.37 (m, 3 H), 7.50–7.53 ppm (m, 2 H); 13 C NMR (75 MHz, CDC1 3 ): δ =82.6, 93.0, 122.8, 123.1, 127.0, 127.2, 128.3, 128.3, 131.3, 131.8 ppm.…”

The Usefulness of Phosphorus Compounds in Alkyne Synthesis

“…Owing to the suitable selection and arrangement of electron-withdrawing groups R 1 and R 2 , the b-keto ylides 10 were conveniently modified to allow the preparation of an unlimited number of precursors. The generation of alkynes 5 from 10 was accomplished by heating the acylmethylenetriphenylphosphoranes 10 at 220-280 °C under vacuum (10)(11)(12)(13)(14)(15)(16) with distillation of the alkynes 5 (Scheme 2).…”

“…This elegant synthetic procedure has been successfully developed with phosphorane precursors 10 containing at least one electron-withdrawing group R 1 [R 1 = aryl, 7,8,[12][13][14][15][16][17] CO 2 R, [8][9][10][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] COSMe, 36 CN, [37][38][39][40][41][42][43][44][45] CHO, 46 COR, 20,47,48 SR, 49,50 SeR, 51,52 P(O)(OPh) 2…”

“…For example, the synthesis of fluorinated alkynes, containing perfluoroalkyl or perfluoroaryl groups, by the pyrolysis of the corresponding b-keto ylides was of considerable importance. Thus, a large variety of phosphonium salts containing electron-withdrawing groups R 1 [R 1 = CN, 38,[65][66][67][68] 69,70 CONR 2 , 71 COSMe, 36 CHO, 72 COR, 73,74 alkenyl, 75 aryl, [12][13][14][15][16][17][76][77][78] aryloxy, 79 2-thienyl 80 ] and perfluorinated groups R 2 were prepared and thermally decomposed to give the corresponding alkynes in moderate to excellent yield.…”

Copper-Catalyzed Coupling Reaction of Terminal Alkynes with Aryl- and Alkenyliodonium Salts

“…This copper-catalyzed cross-coupling method was extended to electron-deficient alkynes. Ethyl propiolate was reacted with iodonium salts 2a and 2c to afford the aryl-substituted propiolates 3n and 3o in 68 and 62% yields, respectively (entries 14 and 15) 1 Cu-Catalyzed Cross-Coupling of Terminal Alkynes with Hypervalent Iodonium Salts …”