Metrics & MoreArticle Recommendations CONSPECTUS: Chemo-and stereoselective transformations of polyborylalkanes are powerful and efficient methods to access optically active molecules with greater complexity and diversity through programmed synthetic design. Among the various polyborylalkanes, gem-diborylalkanes have attracted much attention in organic chemistry as versatile synthetic handles. The notable advantage of gem-diborylalkanes lies in their ability to generate two key intermediates, α-borylalkyl anions and (gem-diborylalkyl) anions. These two different intermediates can be applied to various enantioselective reactions to rapidly access a diverse set of enantioenriched organoboron compounds, which can be further manipulated to generate various chiral molecule libraries via stereospecific C(sp 3 )−B bond transformations.In this Account, we summarize our recent contributions to the development of catalytic chemo-and stereoselective reactions using gem-diborylalkanes as versatile nucleophiles, which can be categorized as follows:(1) copper-catalyzed enantioselective coupling of gem-diborylalkanes with electrophiles and (2) the design and synthesis of (diborylmethyl)metallic species and their applications to enantioselective reactions. Since Shibata and Endo reported the Pdcatalyzed chemoselective Suzuki−Miyaura cross-coupling of gem-diborylalkanes with organohalides in 2014, Morken and Hall subsequently developed the first enantioselective analogous reactions using TADDOL-derived chiral phosphoramidite as the supporting ligand of a palladium catalyst. This discovery sparked interest in the catalytic enantioselective coupling of gemdiborylalkanes with electrophiles. Our initial studies focused on generating chiral (α-borylmethyl)copper species by enantiotopicgroup-selective transmetalation of gem-diborylalkanes with chiral copper complexes and their reactions with various aldimines and ketimines to afford syn-β-aminoboronate esters with excellent enantio-and diastereoselectivity. Moreover, we developed the enantioselective allylation of gem-diborylalkanes that proceeded by reaction of in situ-generated chiral (α-borylalkyl)copper and allyl bromides. Mechanistic investigations revealed that the enantiotopic-group-selective transmetalation between gem-diborylalkanes and the chiral copper complex occurred through the open transition state rather than the closed transition state, thereby effectively generating chiral (α-borylmethyl)copper species. We also utilized (diborylmethyl)metallic species such as (diborylmethyl)silanes and (diborylmethyl)zinc halides in catalytic enantioselective reactions. We succeeded in developing the enantiotopic-group-selective cross-coupling of (diborylmethyl)silanes with aryl iodides to afford enantioenriched benzylic 1,1-silylboronate esters, which could be used for further consecutive stereospecific transformations to afford various enantioenriched molecules. In addition, we synthesized (diborylmethyl)zinc halides for the first time by the transmetalation of isolated (diborylmeth...

Reported herein is the efficient synthesis of tetra-and tri-substituted (Z)-fluoro-and (Z)-chloroborylalkenes by the Boron-Wittig reaction of ketones and aldehydes with bench-top stable halo-diborylmethanes. The substrate scope is broad and the Boron-Wittig reaction proceeds from a diverse range of ketones and aldehydes including biologically relevant molecules with fluoro-or chloro-diborylmethanes, providing tetraand tri-substituted (Z)-fluoro-and (Z)-chloro-borylalkenes in good yields with high stereoselectivity. The utilities of the obtained (Z)-fluoro-and (Z)-chloroborylalkenes are highlighted by further modifications to afford fluoroalkene derivatives or all-carbon substituted alkene.

Here, we report a highly chemo‐, diastereo‐, and enantioselective allyl‐allyl coupling between branched allyl alcohols and α‐silyl‐substituted allylboronate esters, catalyzed by a chiral iridium complex. The α‐silyl‐substituted allylboronate esters can be chemoselectively coupled with allyl electrophiles, affording a diverse set of enantioenriched (E)‐1‐boryl‐substituted 1,5‐dienes in good yields, with excellent stereoselectivity. By permuting the chiral iridium catalysts and the substrates, we efficiently and selectively obtained all four stereoisomers bearing two consecutive chiral centers. Mechanistic studies via density functional theory calculations revealed the origins of the diastereo‐ and chemoselectivities, indicating the pivotal roles of the steric interaction, the β‐silicon effect, and a rapid desilylation process. Additional synthetic modifications for preparing a variety of enantioenriched compounds containing contiguous chiral centers are also included.

Here, we report a highly chemo‐, diastereo‐, and enantioselective allyl‐allyl coupling between branched allyl alcohols and α‐silyl‐substituted allylboronate esters, catalyzed by a chiral iridium complex. The α‐silyl‐substituted allylboronate esters can be chemoselectively coupled with allyl electrophiles, affording a diverse set of enantioenriched (E)‐1‐boryl‐substituted 1,5‐dienes in good yields, with excellent stereoselectivity. By permuting the chiral iridium catalysts and the substrates, we efficiently and selectively obtained all four stereoisomers bearing two consecutive chiral centers. Mechanistic studies via density functional theory calculations revealed the origins of the diastereo‐ and chemoselectivities, indicating the pivotal roles of the steric interaction, the β‐silicon effect, and a rapid desilylation process. Additional synthetic modifications for preparing a variety of enantioenriched compounds containing contiguous chiral centers are also included.

Reported herein is the efficient synthesis of tetra-and tri-substituted (Z)-fluoro-and (Z)-chloroborylalkenes by the Boron-Wittig reaction of ketones and aldehydes with bench-top stable halo-diborylmethanes. The substrate scope is broad and the Boron-Wittig reaction proceeds from a diverse range of ketones and aldehydes including biologically relevant molecules with fluoro-or chloro-diborylmethanes, providing tetraand tri-substituted (Z)-fluoro-and (Z)-chloro-borylalkenes in good yields with high stereoselectivity. The utilities of the obtained (Z)-fluoro-and (Z)-chloroborylalkenes are highlighted by further modifications to afford fluoroalkene derivatives or all-carbon substituted alkene.