Palladium-Catalyzed Synthesis of Dibenzophosphole Oxides via Intramolecular Dehydrogenative Cyclization

Abstract

Dibenzophosphole oxides were obtained from secondary hydrophosphine oxides with a biphenyl group by dehydrogenation via phosphine-hydrogen and carbon-hydrogen bond cleavage in the presence of a catalytic amount of palladium(II) acetate, Pd(OAc)(2). By using this reaction, a ladder-type dibenzophosphole oxide could also be synthesized by double intramolecular dehydrogenative cyclization.

Synthesis of Annelated Phospholes through Intramolecular CH Activation by Monovalent Phosphorus

“…[3] Champion and Cowley described the intramolecular insertion of P I into the C À H bond of the vicinal tertbutyl group of the transient [Fe(CO) 4 ]/supermesitylphosphinidene complex. A logical testing ground for this idea was the family of 1,1'-biaryl-2-phosphinidene complexes [1,1'-Ar-Ar-2-P-W(CO) 5 ]. A logical testing ground for this idea was the family of 1,1'-biaryl-2-phosphinidene complexes [1,1'-Ar-Ar-2-P-W(CO) 5 ].…”

Palladium‐Catalyzed ortho‐Selective CH Borylation of 2‐Phenylpyridine and Its Derivatives at Room Temperature

“…

Direct C À H bond transformations have received much attention as ideal and highly efficient methods for the synthesis of useful organic compounds. [2,3] This is a new concept for the directing group; the group also has an electron pair, but coordinates to a Lewis acidic main-group metal, and a boron atom that also bears a hydrogen atom, which is then converted into a reactive species for C À H activation upon treatment with a transition metal (Scheme 1 b). To solve this problem, directing groups bearing the unshared electron pair of a heteroatom have been used, resulting in dramatic development of the chemistry of C À H bond transformations over the last few decades.

…”

“…2-Phenylpyridine with an electron-donating group at the para-position of the benzene ring, 1 b, produced ortho-borylated 2-phenylpyridine 3 b in 83 % yield in the presence of a palladium catalyst, Pd(OAc) 2 (Table 1, entry 1). 2-Phenylpyridine with an electron-donating group at the para-position of the benzene ring, 1 b, produced ortho-borylated 2-phenylpyridine 3 b in 83 % yield in the presence of a palladium catalyst, Pd(OAc) 2 (Table 1, entry 1).…”

The Development of Novel C-H Bond Transformations and Their Application to the Synthesis of Organic Functional Molecules

“…28 31 π Conjugated molecules containing heteroatom(s), such as sila uorene derivatives, have important uses as organic functional materials such as uorophores, and in solar cell devices. We have reported the synthesis of sila uorene derivatives 28,29 and phospha uorene oxides 30 by intramolecular C H/heteroatom H coupling reactions. Another strategy for the synthesis of heteroatom containing π conjugated molecules is C H/C H coupling reaction of heteroatom bridged biaryl compounds (Scheme 19).…”