A General Method for Interconversion of Boronic Acid Protecting Groups: Trifluoroborates as Common Intermediates

Abstract

We have developed a general protocol for the interconversion of diverse protected boronic acids, via intermediate organotrifluoroborates. N-Methyliminodiacetyl boronates, which have been hitherto resistant to direct conversion to trifluoroborates, have been shown to undergo fluorolysis at elevated temperatures. Subsequent solvolysis of organotrifluoroborates in the presence of trimethylsilyl chloride and a wide range of bis-nucleophiles enables the generation of a variety of protected boronic acids.

Stereoselective Desymmetrization of gem‐Diborylalkanes by “Trifluorination”

“…We were intrigued to observe that gem ‐diborylalkanes ( 11 ) could be selectively converted, for the first time, into gem ‐diboryls containing a boronic acid moiety (B(OH) 2 ) (see 19 ) through a simple hydrolysis process as described in Scheme A . Gratifyingly, the gem ‐diborylalkanes‐BF 3 K ( 11 ) can be directly converted to different unsymmetrical gem ‐diborylalkanes ( 20 – 21 , Scheme B) …”

“…[23] Gratifyingly,t he gem-diborylalkanes-BF 3 K( 11) can be directly converted to differentu nsymmetrical gem-diborylalkanes (20)(21)Scheme 4B). [24] Next, we tried the Pd-catalyzed inter-and intramolecular Suzuki-Miyaura cross-coupling reaction on 11 (Scheme 5D). Such ac ross-couplingr eaction has been reported by Hall, [12] Yun, [13] and Molander [11] on differents ystemsw ith gem-B(dan)-BF 3 Ka nd gem-azaborine-BF 3 K( Schemes5A-C).…”

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

“…[10] Indeed, additions to vinylBpin (14)a re capricious and often low-yielding. [11] Ther obustness of MIDAb oronates [12] is not an advantage in the present context. [8b] In light of these observations,w ec onsidered the two alternative approaches depicted in Scheme 2, hinging on the use of apinacolato boronate to stabilize the initial radical.…”

Synthesis and Modular Reactivity of Pyrazole 5-Trifluoroborates: Intermediates for the Preparation of Fully Functionalized Pyrazoles

“…Boronamides are known to be inert to transmetalation 9 and so these offered the prospect of developing a new series of modular intermediates. Pleasingly, employing a similar approach to that described by Churches et al 10 , treatment of the pyrazole trifluoroborate 1 with TMSCl, 1,8-diaminonaphthalene and triethylamine yielded the desired 5-Bdan product 23 in 77% yield.…”