Synthesis of allylacetylenes from terminal acetylenes and allyl halides

Synthesis of Biaryls via a Nickel(0)-Catalyzed Cross-Coupling Reaction of Chloroarenes with Arylboronic Acids

“…The cross-coupling reaction catalyzed by palladium or nickel complexes often affords unexpected byproducts including the homocoupling products of electrophiles and organometallics. The reaction of Grignard reagents has suffered from the homocoupling resulting from the metal−halogen exchange. , The metathesis of RMX to R 2 M and MX 2 (M = Ni, Pd) produced both dimers of electrophiles and organometallics . The oxidative addition of the metal−carbon bonds to the low-valent transition-metals 29 or their oxidation with oxygen or other oxidizing sources 30 has been another route leading to the dimer of organometallics.…”

“…The use of an additional phosphine ligand apparently gave better results in most cases. It is interesting that benzene was advantageous over dioxane for chloroarenes sensitive to bases, whereas the inorganic base is insoluble in such solvent (entries [27][28][29][30][31]. It was more difficult to achieve high yields in the reaction of mesitylboronic acid due to its large steric hindrance in the transmetalation step.…”

Ring-Closing Metathesis of Co2(CO)6–Alkyne Complexes for the Synthesis of 11-Membered Dienediynes: Overcoming Thermodynamic Barriers

“…In this case, the Cu-catalyzed allylation of the terminal acetylene was a suitable alternative to organometallic reagents. 23 Although this reaction is known as a general method for the introduction of allyl moiety and has been extensively applied in the synthesis of natural products, 24,25 and even in the synthesis of enediyne systems, 26 a one-pot technique for the TMS-group removal/allylation has been reported only once for the KF/CuI-mediated allylation of TMS phenylacetylene in DMF at 80 °C. 27 In our case, much milder conditions were employed: addition of CuI and then allyl bromide to a prestirred mixture of acetylenes 12 and 13 with K 2 CO 3 /MeOH in DMF at room temperature gave the desired enyne 14 in high yield (90%).…”

“…It was possible to use this mixture ( 12 / 13 ) without separation in the alkylation with allyl bromide under TMS-removal conditions in one pot. In this case, the Cu-catalyzed allylation of the terminal acetylene was a suitable alternative to organometallic reagents . Although this reaction is known as a general method for the introduction of allyl moiety and has been extensively applied in the synthesis of natural products, , and even in the synthesis of enediyne systems, a one-pot technique for the TMS-group removal/allylation has been reported only once for the KF/CuI-mediated allylation of TMS phenylacetylene in DMF at 80 °C .…”

Synthesis of Isoxazoline-Fused Bicyclic Enediynes via Intramolecular Nitrile Oxide-Alkene Cycloaddition

“…We started the synthesis of the cycloaddition precursor by carrying out sequential Sonogashira coupling 6 of 1,2-diiodobenzene with THPprotected propargyl alcohol and TMS-acetylene to produce 5. After desilylation, the terminal alkyne carbon was allylated 7 with allyl bromide in the presence of K 2 CO 3 and copper iodide using acetone as solvent to produce the alkene 7. The alcohol 8 obtained upon deprotection of the THP ether was converted to the corresponding aldehyde 9 with Dess-Martin reagent.…”