An operationally simple deaminative borylation reaction of primary alkylamines has been developed. The formation of electron-donor-acceptor complexes between N-alkylpyridinium salts and bis(catecholato)diboron enables photoinduced single-electron transfer and fragmentation to carbon-centered radicals, which are subsequently borylated. The mild conditions allow a diverse range of readily available alkylamines to be efficiently converted into synthetically valuable alkylboronic esters under catalyst-free conditions.

The use of pyridinium‐activated primary amines as photoactive functional groups for deaminative generation of alkyl radicals under catalyst‐free conditions is described. By taking advantage of the visible light absorptivity of electron donor–acceptor complexes between Katritzky pyridinium salts and either Hantzsch ester or Et3N, photoinduced single‐electron transfer could be initiated in the absence of a photocatalyst. This general reactivity platform has been applied to deaminative alkylation (Giese), allylation, vinylation, alkynylation, thioetherification, and hydrodeamination reactions. The mild conditions are amenable to a diverse range of primary and secondary alkyl pyridiniums and demonstrate broad functional group tolerance.

Small-molecule, biologically active natural products continue to be our most rewarding source of, and inspiration for, new medicines. Sometimes we happen upon such molecules in minute quantities in unique, difficult-to-reach, and often fleeting environments, perhaps never to be discovered again. In these cases, determining the structure of a molecule-including assigning its relative and absolute configurations-is paramount, enabling one to understand its biological activity. Molecules that comprise stereochemically complex acyclic and conformationally flexible carbon chains make such a task extremely challenging. The baulamycins (A and B) serve as a contemporary example. Isolated in small quantities and shown to have promising antimicrobial activity, the structure of the conformationally flexible molecules was determined largely through J-based configurational analysis, but has been found to be incorrect. Our subsequent campaign to identify the true structures of the baulamycins has revealed a powerful method for the rapid structural elucidation of such molecules. Specifically, the prediction of nuclear magnetic resonance (NMR) parameters through density functional theory-combined with an efficient sequence of boron-based synthetic transformations, which allowed an encoded (labelled) mixture of natural-product diastereomers to be prepared-enabled us rapidly to pinpoint and synthesize the correct structures.

A photochemical method for converting aliphatic alcohols into boronic esters is described. Preactivation of the alcohol as a 2‐iodophenyl‐thionocarbonate enables a novel Barton–McCombie‐type radical deoxygenation that proceeds efficiently with visible light irradiation and without the requirement for a photocatalyst, a radical initiator, or tin or silicon hydrides. The resultant alkyl radical is intercepted by bis(catecholato)diboron, furnishing boronic esters from a diverse range of structurally complex alcohols.

1,2‐Bis‐boronic esters are useful synthetic intermediates particularly as the two boronic esters can be selectively functionalized. Usually, the less hindered primary boronic ester reacts, but herein, we report a coupling reaction that enables the reversal of this selectivity. This is achieved through the formation of a boronate complex with an electron‐rich aryllithium which, in the presence of an electron‐deficient aryl nitrile, leads to the formation of an electron donor–acceptor complex. Following visible‐light photoinduced electron transfer, a primary radical is generated which isomerizes to the more stable secondary radical before radical‐radical coupling with the arene radical‐anion, giving β‐aryl primary boronic ester products. The reactions proceed under catalyst‐free conditions. This method also allows stereodivergent coupling of cyclic cis‐1,2‐bis‐boronic esters to provide trans‐substituted products, complementing the selectivity observed in the Suzuki–Miyaura reaction.

A photochemical method for converting aliphatic alcohols into boronic esters is described. Preactivation of the alcohol as a 2‐iodophenyl‐thionocarbonate enables a novel Barton–McCombie‐type radical deoxygenation that proceeds efficiently with visible light irradiation and without the requirement for a photocatalyst, a radical initiator, or tin or silicon hydrides. The resultant alkyl radical is intercepted by bis(catecholato)diboron, furnishing boronic esters from a diverse range of structurally complex alcohols.

The use of pyridinium-activated primary amines as photoactive functional groups for deaminative generation of alkylr adicals under catalyst-free conditions is described. By taking advantage of the visible light absorptivity of electron donor-acceptor complexes between Katritzkypyridinium salts and either Hantzsch ester or Et 3 N, photoinduced singleelectron transfer could be initiated in the absence of ap hotocatalyst. This general reactivity platform has been applied to deaminative alkylation (Giese), allylation, vinylation, alkynylation, thioetherification, and hydrodeamination reactions.The mild conditions are amenable to ad iverse range of primary and secondary alkylp yridiniums and demonstrate broad functional group tolerance.

Decarboxylative halogenations of alkyl carboxylic acids are highly valuable reactions for the synthesis of stucturally diverse alkyl halides. However, many reported protocols rely on stoichiometric strong oxidants or highly electrophilic halogenating agents. Herein, we describe visible‐light photoredox‐catalyzed decarboxylative halogenations of N‐hydroxyphthalimide‐activated carboxylic acids that avoid stiochiometric oxidants and use inexpensive inorganic halide salts as the halogenating agents. Brominations with lithium bromide proceed under simple, transition metal‐free conditions using an organic photoredox catalyst and no other additives, whereas dual photoredox–copper‐catalysis is required for chlorinations with lithium chloride. The mild conditions display excellent functional group tolerance, which is demonstrated through the transformation of a diverse range of structurally complex carboxylic acid‐containing natural products into the corresponding alkyl bromides and chlorides. In addition, we show the generality of the dual photoredox–copper‐catalyzed decarboxylative functionalizations with inorganic salts by extension to a thiocyanation with potasium thiocyanide, which was applied to the synthesis of complex alkyl thiocyanates.