Aminoboranes via Tandem Iodination/Dehydroiodination for One-Pot Borylation

Abstract

A rapid synthesis of aminoboranes from amine-boranes utilizing an iodination/dehydroiodination sequence is described. Monomeric aminoboranes are generated exclusively from several substrate adducts, following an E2-type elimination, with the added base playing a critical role in monomer vs dimer formation. Diisopropylaminoborane formed using this methodology has been applied to a one-pot palladium-catalyzed conversion of iodo- and bromoarenes to the corresponding boronates. Additionally, modification of the workup allows for isolation of the boronic acid and recovery of the utilized amine.

Monotrifluoroacetoxyborane-amines: chemoselective reagents for challenging reductive aminations

“…A similar chemical shift was observed when 2a was treated with other 11-, 21-and 31-amines, except pyridine. We hypothesized that the TFAB-NH 3 complex is deprotonated by the added amines followed by elimination of TFA to generate the amino-borane species in a dehydroacetoxylation process, similar to the previously reported dehydrohalogenation process with iodoborane- 13 or chloroborane-amine 14 complexes. This was reinforced when TFAB-NEt 3 did not undergo similar deprotonation by amines.…”

In situ generated aminodiborane as a reagent for deoxygenative reduction of carboxamides to amines

“…S4 †). 6 This observation indicated the possibility that the active reagents in the case of tertiary amides are aminodiborane and polyaminoboranes. 16…”

“…Ramachandran and co-workers have used reactions of elemental iodine (I 2 ) with dialkylamine-boranes to realize haloborane–amine complexes, which were used for the synthesis of arylboronates. 6 Herein, we report a simple synthesis of aminodiborane by the reaction of AB and I 2 with no requirement of an inert atmosphere (Scheme 1d).…”

Synthesis: Molecular Structure, Thermal-Calorimetric and Computational Analyses, of Three New Amine Borane Adducts

“…However, many other ABAs have been developed in parallel, not necessarily for being used as a hydrogen carrier, thus for various uses in chemistry. Examples are follows: ethylenediamine bisborane as hydrogen carrier [ 5 ]; diisopropylaminoborane for one-pot borylation [ 6 ]; morpholine borane as radical initiator [ 7 ]; pyridine borane as reducing agent [ 8 ]; ammonia borane as hydrogenation reagent [ 9 ]; 1,3,5-( p -aminophenyl)benzene-borane as monomer of borazine-linked polymer [ 10 ]; and, methylamine borane as precursor of boron-carbon-nitrogen layers [ 11 ]. Providing an exhaustive list of the ABAs reported so far and of their potential applications goes beyond the scope of the present article, and for further information, the reader is referred to appropriate review articles [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”