Unsymmetrical 1,1-bis(boryl)alkanes and alkenes are organo-bismetallic equivalents, which are synthetically important because they allow for sequential selective transformations of C–B bonds. We reviewed the synthesis and chemical reactivity of 1,1-bis(boryl)alkanes and alkenes to provide information for the synthetic community. In the first part of this review, we disclose the synthesis and chemical reactivity of unsymmetrical 1,1-bisborylalkanes. In the second part, we describe the synthesis and chemical reactivity of unsymmetrical 1,1-bis(boryl)alkenes.

The use of gem-diborylalkenes as light-reactive groups is explored for the first time. These reactions provide an efficient and general method for the photochemical conversion of gem-diborylalkenes to rapidly access 1,1-bisborylalkanes. This method exploits a novel photoredox decarboxylative radical addition to gem-diborylalkenes to afford α-gemdiboryl carbon-centered radicals, which benefit from additional stability by virtue of an interaction with the empty p-orbitals on borons. The reaction offers a highly modular and regioselective approach to γ-amino gem-diborylalkanes. Furthermore, EPR spectroscopy and DFT calculations have provided insight into the radical mechanism underlying the photochemistry reaction.

Organoborons are extremely important for synthetic organic chemistry; they can serve as advanced intermediates for a variety of transformations. Such a well-known transformation involves the loss of the boron moiety, creating alkyl radicals. Although these originally developed protocols for alkyl radical generation remain in active use today, in recent years their α-boryl carbon-centred radicles have been joined by a new array of radical generation strategies that offer a unique reactivity to forge a wider diversity of organoborones that often operate under mild and benign conditions. Herein, we will highlight the stability and reactivity of α-borylalkyl radicals and their remarkably recent advances in order to further utilise them for C–C and C–heteroatom bond formation. Their use for this purpose has been reported over the last decade in an attempt to guide the synthetic community. Various transition-metal and metal-free methods for their generation are presented, and more advanced photoredox approaches are discussed, mainly for the period of time 2009-2019.

In the past four decades, the chemistry of 1,1‐ and 1,2‐bisboronate compounds has been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal‐catalyzed and metal‐free transformations for the formation of CC bonds and C–heteroatom and other processes. This chapter aims to highlight the recent development in this rising research field, focusing on the synthesis of 1,1‐ and 1,2‐bisboronate compounds and their reactivity and selectivity that originate from the use of these bisboronates.

An efficient and general method for the chemoselective synthesis of unsymmetrical gem-diborylalkanes is reported. This method is based on a novel late-stage desymmetrization via nucleophilic “trifluorination”, providing chiral gem-diborylalkanes bearing a trifluoroborate group. The reaction offers a highly modular and diastereoselective approach to synthesize gem-diborylcyclopropanes. The utility of the gem-diborylalkane building blocks was demonstrated by selective post-functionalization of the trifluoroborate group. These functionalizations include inter- and intra- Pd-catalyzed Suzuki−Miyaura coupling reactions.

Recently, gem-diborylalkanes have attracted much attention as versatile building blocks and fundamental intermediates in organic synthesis, because they enable multiple C–C bond construction and further transformation at C–B bonds. Importantly, gem-diborylalkanes can be utilised as bisnucleophilic partners in a variety of chemo-selective C–C bond-forming reactions. This review describes recent developments in synthesising gem-diborylalkanes in complex molecules along with their chemical transformation. In the first part of the review the different synthetic approaches used to synthesise gem-diborylalkanes are described. In the second part, an overview of the chemoselective transformation of gem-diborylalkanes into various functionalized materials is discussed along with one-carbon homologation of diborylmethane via a selective uni- and bidirectional method.

Several approaches using organozirconocene species for the remote cleavage of strained three-membered ring carbocycles are described. -Ene polysubstituted cyclopropanes, alkylidenecyclopropanes, -ene spiro[2.2]pentanes and -ene cyclopropyl methyl ethers were successfully transformed into stereodefined organometallic intermediates allowing an easy access to highly stereoenriched acyclic scaffolds in good yields and in most cases excellent selectivities. DFT calculations and isotopic labeling experiments were performed to delineate the origin of the obtained chemo- and stereoselectivities, demonstrating the importance of microreversibility.