First Unambiguous Characterization of a Novel RO-BH₂ Intermediate by ¹H{¹¹B} and ¹H{¹³C,¹¹B} NMR Spectroscopy. Proof of Boron−Carbonyl Interaction through Innovative Use of NMR Techniques

Abstract

An unusual reduction of the aryl-substituted 3-hydroxyacrylic acid ester 1 by BH 3 results in the propenoic acid ethyl ester 3. We were able to proVe the presence of an intermediate 2 containing a cyclic O-BH 2 r OdC< moiety in 2 by using 1 H-11 B and 1 H-13 C{ 11 B} NMR correlation experiments.

A Stereocontrolled Synthesis of a Phosphorothioate Cyclic Dinucleotide-Based STING Agonist

“…The lowest yielding reaction was the nonselective LiBH 4 -mediated deprotection of the benzoylated alcohol proximal to the hydroxycyclobutane, 16 → 17 . Attempts to improve on this deprotection centered around invoking the previously reported bicyclic syn -Alanate transition states encountered during the ketone reduction step, although all attempts at selective deprotection, including LiAlH 4 and BH 3 , failed.…”

Seven membered ring chelates derived from γ-hydroxyamides and triphenyltin or diphenylboron

“…An O ? BH 2 O seven membered chelate was recently reported [16]. However, X-ray diffraction analyses for compounds forming seven membered rings by carbonyl coordination to boron are unknown.…”