Nucleophilic Neutral Diborane(4) Compounds with sp³–sp³‐Hybridized Boron Atoms

Abstract

Borylation reactions with diborane(4) compounds are of key importance in modern synthetic chemistry. Generally, sp 2 -sp 2 -hybridized diborane(4) compounds are used for this purpose; these can be regarded as boryl-substituted boranes and consequently react as electrophiles. In contrast, the chemistry of nucleophilic, electron-rich sp 3 -sp 3 -hybridized diborane (4)

Catalyst‐Free Hydroboration of CO2 With a Nucleophilic Diborane(4)

“…[16] Herein, we report the first catalyst-free hydroboration of CO 2 with an eutral boron compound, the nucleophilic sp 3 -sp 3 hybridized diborane[ HB(hpp)] 2 (hpp = 1,3,4,6,7,8-hexahydro-2Hpyrimido[1,2-a]pyrimidinate), 1. [17][18][19] Our results pave the way for the use of nucleophilic diboranes in hydroboration Scheme1.a) Hydroboration of CO 2 with electrophilicH B 9BBN ,c atalyzed by PtBu 3 (Stephan et al). [8] b) Catalytic reaction of CO 2 with an electrophilic diborane( Sadighi et al).…”

Chemistry of Dicationic Diboranes

“…Remarkably, the Ghosh group recently reported the first structurally characterized bimetallic diborane(4) complex of B 2 H 4 , [(Cp * Mo) 2 (CO) 4 (B 2 H 4 )]. [14] The boron chemistry investigated by our group within the last years mainly concentrates on guanidinate-substituted diboron(4) compounds, and especially on [HB(hpp)] 2 (2) (hpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-α]pyrimidinate).…”

Boron−Boron Dehydrocoupling of Boranes Initiated by Reaction with Iodine

“…As mentioned in the introduction, the motivation for this work was the synthesis of new diborane(4) compounds that are related to the intensely studied strongly nucleophilic compound [HB(μ‐hpp)] 2 , but differ in the bridging substituents. The nucleophilicity of diborane(4) compounds with bridging hpp and L substituents was compared through quantum‐chemical calculations on the compounds [XB(μ‐ L )] 2 and [XB(μ‐hpp)] 2 (X=H or I).…”

“…Due to the electron‐donating effect of the guanidinate groups (see mesomeric structures in Scheme a), the diborane(4) [HB(μ‐hpp)] 2 is strongly nucleophilic, which is different from most other diborane(4) derivatives. This strong nucleophilicity is the reason for its unusual and diverse chemistry, which has been extensively studied by our group …”