Tetraethylphosphorodiamidate-Directed Metalation Group: Directed Ortho and Remote Metalation, Cross Coupling, and Remote Phospha Anionic Fries Rearrangement Reactions

Advancement in Synthetic Strategies of Phosphorus Heterocycles: Recent Progress from Synthesis to Emerging Class of Optoelectronic Materials

Organophosphorus heterocycles have long been acknowledged for their significant potential across diverse fields, including catalysis, material science, and drug development. Incorporating phosphorus functionalities into organic compounds offers a means to effectively tailor their medicinal properties, augment biological responses, and enhance selectivity and bioavailability. The distinctive physical and photoelectric characteristics of phosphorus-containing conjugated compounds have garnered considerable interest as promising materials for organic optoelectronics. These compounds find extensive utility in various applications such as light-emitting diodes, photovoltaic cells, phosphole-based fluorophores, and semiconductors.

The Versatile and Strategic O-Carbamate Directed Metalation Group in the Synthesis of Aromatic Molecules: An Update

The aryl O-carbamate (ArOAm) group is among the strongest of the directed metalation groups (DMGs) in directed ortho metalation (DoM) chemistry, especially in the form Ar-OCONEt2. Since the last comprehensive review of metalation chemistry involving ArOAms (published more than 30 years ago), the field has expanded significantly. For example, it now encompasses new substrates, solvent systems, and metalating agents, while conditions have been developed enabling metalation of ArOAm to be conducted in a green and sustainable manner. The ArOAm group has also proven to be effective in the anionic ortho-Fries (AoF) rearrangement, Directed remote metalation (DreM), iterative DoM sequences, and DoM-halogen dance (HalD) synthetic strategies and has been transformed into a diverse range of functionalities and coupled with various groups through a range of cross-coupling (CC) strategies. Of ultimate value, the ArOAm group has demonstrated utility in the synthesis of a diverse range of bioactive and polycyclic aromatic compounds for various applications.

Regioselective Substitution of BINOL

1,1'-Bi-2-naphthol (BINOL) has been extensively used as the chirality source in the fields of molecular recognition, asymmetric synthesis, and materials science. The direct electrophilic substitution at the aromatic rings of the optically active BINOL has been developed as one of the most convenient strategies to structurally modify BINOL for diverse applications. High regioselectivity has been achieved for the reaction of BINOL with electrophiles. Depending upon the reaction conditions and substitution patterns, various functional groups can be introduced to the specific positions, such as the 6-, 5-, 4-, and 3-positions, of BINOL. Ortho-lithiation at the 3-position directed by the functional groups at the 2-position of BINOL have been extensively used to prepare the 3- and 3,3'-substituted BINOLs. The use of transition metal-catalyzed C-H activation has also been explored to functionalize BINOL at the 3-, 4-, 5-, 6-, and 7-positions. These regioselective substitutions of BINOL have allowed the construction of tremendous amount of BINOL derivatives with fascinating structures and properties as reviewed in this article. Examples for the applications of the optically active BINOLs with varying substitutions in asymmetric catalysis, molecular recognition, chiral sensing and materials are also provided.

Organophosphates as Versatile Substrates in Organic Synthesis

This review summarizes the applications of organophosphates in organic synthesis. After a brief introduction, it discusses cross-coupling reactions, including both transition-metal-catalyzed and transition-metal-free substitution reactions. Subsequently, oxidation and reduction reactions are described. In addition, this review highlights the applications of organophosphates in the synthesis of natural compounds, demonstrating their versatility and importance in modern synthetic chemistry.

Transition Metal-Free Synthesis of Halobenzo[b]furans from O-Aryl Carbamates via o-Lithiation Reactions

A straightforward and transition metal-free one-pot protocol to synthesize halobenzo[b]furans has been developed employing simple and easily available starting materials such as O-aryl carbamates and alkynylsulfones. The fine-tuning of the different steps involved was key to achieving a successful one-pot procedure. Initially, a directed ortho-lithiation process, which uses the carbamate as the directed metalation group, was crucial in providing access to O-2-alkynylaryl N,N-diethyl carbamates by a direct alkynylation of the o-lithiated carbamate, with arylsulfonylalkynes as electrophilic reagents. Cyclization of the generated o-alkynylaryl carbamates was successfully accomplished through a strategy involving in situ carbamate alkaline hydrolysis under conventional heating or microwave irradiation, coupled with a subsequent heterocyclization step delivering the desired benzo[b]furans. A wide variety of new halobenzo[b]furans has been synthesized and their utility has been demonstrated by their further transformation.

Selective Synthesis of C1-Symmetric BINOL-phosphates and P-chiral Phosphoramides Using Directed ortho-Lithiation

Directed ortho-lithiation (DoL) has been developed as an effective method for the ortho-substitution of BINOL-phosphoric acid and BINOL-N-triflylphosphoramide (BINOL-P-acids). It can be employed in the rapid assembly of either mono- or disubstituted BINOL-P-acids, including unsymmetrical disubstitution through iterative DoL. Most significantly, DoL has proven to be highly effective in the diastereoselective desymmetrization of pseudo-C₂-symmetric BINOL-N-triflylphosphoramide, affording a chiral P-group.

Directed Ortho and Remote Metalation of Naphthalene 1,8-Diamide: Complementing SEAr Reactivity for the Synthesis of Substituted Naphthalenes

Mono- and dianion species of 1,8-naphthalene diamide 2 were generated under sec-BuLi/TMEDA conditions and trapped with a variety of electrophiles to give 2- and 2,7- substituted products 3 and 4. Using Suzuki-Miyaura cross-coupling, mono- and di-iodinated products were converted into the corresponding 2-aryl (5) and 2,7-diaryl (6) products, respectively. The amide-amide rotation barrier of 2 was established by VT NMR, and the structure of fluorenone structure 9, obtained by remote metalation, was secured.