Conversion of Dibenzoxaphosphinines into 2‐Hydroxybiphenyl‐2′‐ylphosphane Ligands and Their BH₃ Adducts: The O–H^δ+···H^δ––B Hydrogen–Hydrogen Bond

Abstract

1 , which underwent ring-opening metathesis with less bulky organolithium compounds R 2 Li. After O-trimethylsilylation, 2-(trimethylsilyloxy)biphenylylphosphanes 2 were isolated. Reaction of 1 Cl with R 2 Li followed by silylation provided symmetrically P-substituted compounds 2. The formation of compounds 3 and 4 demonstrated the facile hydrolysis and oxidation of 1 R 1 , the formation of compound 5c ox indicated the sensitivity of 2 to hydrolysis and air oxidation. Methanolysis of 2 provided the free hydroxybiphenylylphosphanes 5 (for further modification by O-acylation), which were converted into air-stable borane adducts 6. The latter

Synthesis, Characterization, and Coupling Reactions of Six-Membered Cyclic P-Chiral Ammonium Phosphonite–Boranes; Reactive H-Phosphinate Equivalents for the Stereoselective Synthesis of Glycomimetics

“…Thus, a so-called dihydrogen bond between the hydridic hydrogen of phosphine boranes and the acidic hydrogen of phenols has been advanced based on crystallographic evidence. 58 Accordingly, the possibility exists of such a dihydrogen bond between the incoming alcohol and the borane of one or more of the likely intermediates and that it directs the alcohol to the same face of the system as the borane moiety in a solvent-dependent manner. The possibility that donor−acceptor hydrogen bonding directs glycosylation reactions 59 has been raised in recent years and is a subject of ongoing discussion in the literature.…”

“…One final unknown is the extent to which, if any, dihydrogen bonding intervenes to direct the incoming nucleophile. Thus, a so-called dihydrogen bond between the hydridic hydrogen of phosphine boranes and the acidic hydrogen of phenols has been advanced based on crystallographic evidence . Accordingly, the possibility exists of such a dihydrogen bond between the incoming alcohol and the borane of one or more of the likely intermediates and that it directs the alcohol to the same face of the system as the borane moiety in a solvent-dependent manner.…”

Transition-metal-free synthesis of functional 2-arylphenols by an intermolecular SNAr reaction between dibenzofurans and various nucleophiles

“…Therefore, the development of an efficient and highly atom economical method for the construction of this motif is highly attractive. 6…”