Cracked under strain: Strained allylic cyclobutanols and cyclopropanols readily undergo a ring expansion described by the title rearrangement. This reaction is promoted by catalytic amounts of 1 and displays high tolerance with respect to the substrate scope. The corresponding β‐fluoro spiroketone products are isolated in high yields and with excellent stereoselectivities. EDG=electron‐donating group
the heavier halogens (bromine and iodine) second, the scope and limitations of the halogenative phase‐transfer methodology will be discussed and compared. An extension of the fluorination/semi‐pinacol reaction to the ring‐expansion of five‐membered allylic cyclopentanols will be also described, as well as some preliminary results on substrates prone to desymmetrization will be given. Finally, the present
The present manuscript describes a high-yielding enantioselective semipinacol transposition, initiated by an electrophilic iodination event. The title transformation makes use of the anionic phase-transfer catalysis (PTC) paradigm for chirality induction. Thus, when combined appropriately, the insoluble cationic iodinating reagent S9 and the lipophilic phosphoric acid L9 act as an efficient source
A New Biarylphosphine Ligand for the Pd-Catalyzed Synthesis of Diaryl Ethers under Mild Conditions
作者:Luca Salvi、Nicole R. Davis、Siraj Z. Ali、Stephen L. Buchwald
DOI:10.1021/ol202955h
日期:2012.1.6
A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C–O cross-coupling of a wide range of aryl halides and phenols undermilderconditions than previously possible. A direct correlation between the size of the ligand substituents in the 2′, 4′, and 6′ positions of the nonphosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically
Iron-catalyzed regioselective cyclotrimerization of alkynes to benzenes
作者:Suhas Shahaji Gawali、Chidambaram Gunanathan
DOI:10.1016/j.jorganchem.2018.12.007
日期:2019.2
catalyzed the regioselective [2+2+2] cyclotrimerization of terminal aryl and alkyl alkynes to provide the 1,2,4-trisubstituted benzene molecules. Interestingly, internal alkynes also exhibited similar cyclization and resulted in hexa-substituted benzene compounds. Increased steric bulk on pincer ligands diminished the selectivity for cycloaddition. Cyclotrimerization reactions proceeded at room temperature