Pd(0)-Catalyzed Cyclizative Carboboration of n-Iodo-1,6-diene (n = 1 or 2): Access to Structurally Complex Allylboronates and Alkylboronates

Photochemical carboborylation and three-component difunctionalization of α,β-unsaturated ketones with boronic acids via tosylhydrazones

The reactions of cyclic α,β-unsaturated N-tosylhydrazones and alkylboronic acids promoted by 370-390 nm light in the presence of a base give rise to allylic boronic acids that can be trapped as the corresponding pinacolboronates by treatment with pinacol. This reaction features wide scope regarding both coupling partners and functional group tolerance, allowing for the incorporation of a variety of natural product-derived fragments. The allylic boronic acids can be also reacted in a one-pot process with aldehydes, to produce homoallylic alcohols with very high diastereoselectivity. A three-component one-pot procedure has been developed revealing that the methodology is a powerful tool for the generation of structural diversity that is accomplished by incorporation of an ample variety of each of the three elements. Moreover, from a synthetic perspective, in the reaction, the formation of two C-C bonds, at the carbonyl and the β positions of a α,β-unsaturated carbonyl, has been achieved in the three-component reaction.

Three-component cascade carbopalladation/Heck cyclization/borylation: facile access to boryl-functionalized indenes

A mild Pd-catalyzed three-component cascade cyclization functionalization of o-iodostyrenes, internal alkynes and boron reagents is presented. The transformation is driven by a controlled reaction sequence of intermolecular carbopalladation, intramolecular Heck-type cyclization, and a borylation process to give versatile boryl-functionalized indene skeletons in a selective fashion. Significantly, (Bpin)2, (Bneop)2 and CH2(Bpin)2 as boron sources are all tolerated. Additionally, the synthetic utility of this approach is demonstrated by gram-scale synthesis and synthetic transformations.

Palladium-Catalyzed Heck/Suzuki Tandem Reaction of (Z)-1-Iodo-1,6-dienes and Organoboronic Acids

The Heck/Suzuki tandem reaction has emerged as an essential strategy for the synthesis of complex molecules. Herein, an efficient palladium-catalyzed Heck/Suzuki tandem reaction of (Z)-1-iodo-1,6-dienes with organoboronic acids is described, providing various tetrahydropyridines in good to excellent yields under mild reaction conditions. The key to the success of this approach is the avoidance of the intramolecular second Heck insertion occurring prior to the transmetalation step. In addition, the asymmetric version of this reaction is investigated to deliver chiral tetrahydropyridine in excellent yield with promising enantioselectivity.

Palladium-Catalyzed Borylative Cyclization and Cyclopropanation of Terminal Alkyne-Derived Enynes

Described herein is a palladium-catalyzed borylative cyclization and cyclopropanation of terminal alkyne-derived enynes, affording borylated bicycles, fused cycles, and bridged cycles in good isolated yields. The synthetic utility of this protocol was fully demonstrated by large scale reaction and synthetic derivatization of the borate group.

Catalytic enantioselective alkenylation-heteroarylation of olefins: stereoselective syntheses of 5-7 membered azacycles and oxacycles

Catalytic enantioselective domino alkenylation-heteroarylation of nonconjugated iododienes proceeded with excellent stereoselectivity and broad scope of substrates. The reaction enables stereoselective syntheses of substituted azacycles such as piperidine, pyrrolidine azepine and dihydropyrans carrying new quaternary stereocenters. Mechanistically, C-H bonds of heterocycles were activated by lithium alkoxides via reversible deprotonation, rather than conventional palladium(ii)-assisted metalation processes. Many types of heteroarenes can be used, including not only azoles (such as thiazoles, oxazoles, imidazoles and oxadiazoles), but also nonazoles (thiophene, furan and azine N-oxides).