A Practical and General Synthesis of Unsymmetrical Terphenyls
摘要:
[GRAPHICS]A synthetic procedure was developed that enables sequential chemoselective Suzuki-Miyaura cross-coupling of chlorobromobenzene with arylboronic acids. The first coupling is achieved at room temperature using a ligandless palladium catalyst. The chlorobiaryl product can then be subjected directly to the second coupling, facilitated by the SPhos ligand. Using this methodology, parallel synthesis of 32 unsymmetrical o-, m-, and p-terphenyl compounds was accomplished in good to excellent overall yields.
Iodine Promoted Regioselective α-Sulfenylation of Carbonyl Compounds using Dimethyl Sulfoxide as an Oxidant
作者:Yogesh Siddaraju、Kandikere Ramaiah Prabhu
DOI:10.1021/acs.orglett.6b03084
日期:2016.12.2
A metal-free regioselective sulfenylation of the α-CH3 group of ketones has been achieved in the presence of the α-CH2 or α-CH group using the cross dehydrogenative (CDC) strategy. Aldehydes also exhibit good selectivity forming the corresponding α-sulfenylated products. This efficient sulfenylation of ketones or aldehydes with thiones or heterocyclic thiols utilizes dimethyl sulfoxide (DMSO) as an
With the aid of an ionic liquid, palladium acetate was immobilized in the pores of silica gel, which was coated with polyethylene terephthalate. The heterogeneous catalyst was effective for Suzuki-Miyaura reactions of ortho-substituted aryl bromides, aryl triflates, and arylboronic acids in aqueous ethanol at room temperature, and could be re-used up to ten times.
The synthesis of some substituted biphenyl-4-carboxylic acids, 4-biphenylylacetic acids, and 4-aminobiphenyls
作者:D. J. Byron、G. W. Gray、R. C. Wilson
DOI:10.1039/j39660000840
日期:——
The synthesis of a range of substitutedbiphenyl-4-carboxylicacids and 4-aminobiphenyls is described. Preparations are included for the parent biphenyl-4-carboxylicacid, and for 4-biphenylylaceticacid and three substituted4-biphenylylaceticacids.
Palladium acetate was noncovalently immobilized as a supported ionic liquid catalyst (SILC) in a nanosilica dendrimer, PAMDMAM, with the aid of an ionic liquid to form a cluster catalyst of palladium nanoparticles. The pseudo-homogeneous heterogenized catalyst, Pd-nanoPAMDMAM-SILC, was effective for Suzuki-Miyaura reactions of ortho-substituted aryl bromides or aryl triflates without a ligand in 50% aqueous ethanol in air at room temperature. The catalyst could be re-used up to five times in 93% average yield after simple centrifugation. TON reached 176,000.
Arynes are found to be facilely inserted into bis(pinacolato)diboron by using a platinum–isocyanide catalyst, affording diverse 1,2-diborylarenes, which can be converted into o-terphenyls via Suzuki–Miyaura coupling reaction.