A series of crystalline sp -sp diboron(4) compounds were synthesized and shown to promote the facile reduction of water with dihydrogen formation. The application of these diborons as simple and effective dihydrogen and dideuterium sources was demonstrated by conducting a series of selective reductions of alkynes and alkenes, and hydrogen-deuterium exchange reactions using two-chamber reactors. Finally, as the water reduction reaction generates an intermediate borohydride species, a range of aldehydes and ketones were reduced by using water as the hydride source.

A dual catalytic sp 3 α C−H arylation and alkylation of benzamides with organic halides is described. This protocol exhibits an exquisite site selectivity, chemoselectivity, and enantioselectivity pattern, offering a complementary reactivity mode to existing sp 3 arylation or alkylations via transition metal catalysis or photoredox events.

A Ni-catalyzed reductive deaminative arylation at unactivated sp3 carbon centers is described. This operationally simple and user-friendly protocol exhibits excellent chemoselectivity profile and broad substrate scope, thus complementing existing metal-catalyzed cross-coupling reactions to forge sp3 C–C linkages. These virtues have been assessed in the context of late-stage functionalization, hence providing a strategic advantage to reliably generate structure diversity with amine-containing drugs.

A simple method for accessing perfluoroalkyl-substituted enones is described applying a four-component palladium-catalyzed carbonylative coupling of aryl boronic acids together with terminal alkynes and perfluoroalkyl iodides in the presence of carbon monoxide. A wide range of highly functionalized enones can thus be prepared in a single operation in good yields. With 2-aminophenylalkynes, an intramolecular aminocarbonylation event overrules providing the indolin-2-one framework. Finally, adaptation of the two-chamber technology expands the method to the synthesis of the aforementioned structures with C-isotope labeling.

An unexpected palladium-catalyzed carbonylatives ynthesis of 2,3-disubstituted chromones has been developed. Startingf rom 2-bromofluorobenzenesa nd ketones,t he corresponding chromones were produced in good yields. By control experiments,this transformation was found to proceed through as equential carbonylation/Claisen-Hasse rearrangement/intramolecular nucleophilic aromatic substitution approach (S N Ar). More specifically,t he reaction sequence started with ap alladium-catalyzed carbonylation of the ketone with o-bromofluorobenzene to give the vinyl benzoates,w hich subsequently transformed into 1,3-diketones via aC laisen-Hasse rearrangement. Thef inal products were produced after an intramolecular S N Ar reaction of the in situ formed 1,3-diketone. Scheme 1. Pathways to 2,3-disubstituted chromones.Scheme 2. Thechemoselectivity on carbonylation of the deoxybenzoin substrate.

We report on a three-component palladium-catalyzed coupling strategy for accessing a wide range of 1,4-diketones, which represent important precursors to heterocycles. Our method relies on a carbonylative Heck reaction employing substituted allylic alcohols, aryl iodides, and carbon monoxide. The reaction conditions are mild and do not require high CO pressure, and a wide functional group tolerance is revealed, providing the desired 1,4-diketones in moderate to good yields. Furthermore, the methodology is adaptable to the selective installment of 13C-carbon isotopes at either one or both of the carbonyl positions.

A simple and mild method is demonstrated for assembling acyl carbamates through a base-free four-component Pd-catalyzed carbonylation of aryl halides in the presence of potassium cyanate and alcohols in a two-chamber system. This approach produces a wide range of aryl acyl carbamates in good to excellent yields from the corresponding aryl bromides or iodides with near-stoichiometric carbon monoxide. In addition, the method can be extended to the synthesis of primary amides thereby expanding the usefulness of cyanate as an ammonia equivalent.

A catalytic protocol for the preparation of α,α-difluoro-β-alkyl-β-ketoamides is developed employing a Pd-mediated carbonylative Suzuki coupling between alkylboron reagents and bromodifluoroacetamides with COgen as the CO source. The reaction reveals good functional group tolerance providing a broad selection of α,α-difluoro-β-alkyl-β-ketoamides in moderate to good yields, which represent useful precursors for further synthetic manipulation. Finally, the methodology is amenable to 13C-isotope labeling at the ketone carbon applying 13C-COgen.