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A strategy for the photosensitized cycloaddition of alkenylboronates and allylic alcohols by a temporary coordination is presented. The process allows for the synthesis of a diverse range of cyclobutylboronates. Key to development of these reactions is the temporary coordination of the allylic alcohol to the Bpin unit. This not only allows for the reaction to proceed in an intramolecular manner but also allows for high levels of stereo and regiocontrol. A key aspect of these studies is the utility of the cycloadducts in the synthesis of complex natural products artochamin J and piperarborenine B. 

The crystal structures of three β-halolactic acids have been determined, namely, β-chlorolactic acid (systematic name: 3-chloro-2-hydroxypropanoic acid, C 3 H 5 ClO 3 ) (I), β-bromolactic acid (systematic name: 3-bromo-2-hydroxypropanoic acid, C 3 H 5 BrO 3 ) (II), and β-iodolactic acid (systematic name: 2-hydroxy-3-iodopropanoic acid, C 3 H 5 IO 3 ) (III). The number of molecules in the asymmetric unit of each crystal structure ( Z ′) was found to be two for I and II, and one for III, making I and II isostructural and III unique. The difference between the molecules in the asymmetric units of I and II is due to the direction of the hydrogen bond of the alcohol group to a neighboring molecule. Molecular packing shows that each structure has alternating layers of intermolecular hydrogen bonding and halogen–halogen interactions. Hirshfeld surfaces and two-dimensional fingerprint plots were analyzed to further explore the intermolecular interactions of these structures. In I and II, energy minimization is achieved by lowering of the symmetry to adopt two independent molecular conformations in the asymmetric unit. 

A method for amide-directed Ni-catalyzed diastereoselective arylboration of cyclopentenes is disclosed. The reaction allows for the synthesis of sterically congested cyclopentane scaffolds that contain an easily derivatized boronic ester and amide functional handles. The nature of the amide directing group and its influence on the reaction outcome are investigated and ultimately reflect a predictably selective reaction based on the solvent and base counterion. 

Abstract A new strategy for the synthesis of highly versatile cyclobutylboronates via the photosensitized [2+2]‐cycloaddition of alkenylboronates and alkenes is presented. The process is mechanistically different from other processes in that energy transfer occurs with the alkenylboronate as opposed to the other alkene. This strategy allows for the synthesis of an array of diverse cyclobutylboronates. The conversion of these adducts to other compounds as well as their utility in the synthesis of melicodenine C is demonstrated. 

Abstract A new strategy for the synthesis of highly versatile cyclobutylboronates via the photosensitized [2+2]‐cycloaddition of alkenylboronates and alkenes is presented. The process is mechanistically different from other processes in that energy transfer occurs with the alkenylboronate as opposed to the other alkene. This strategy allows for the synthesis of an array of diverse cyclobutylboronates. The conversion of these adducts to other compounds as well as their utility in the synthesis of melicodenine C is demonstrated.