B(C6F5)3 catalyzed direct nucleophilic substitution of benzylic alcohols: an effective method of constructing C–O, C–S and C–C bonds from benzylic alcohols

One-step synthesis of amphiphilic copolymers PDMS-b-PEG using tris(pentafluorophenyl)borane and subsequent study of encapsulation and release of curcumin

A series of amphiphilic block copolymer (BCP) micelles based on poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEG) were synthesized by a one-step reaction in the presence of tris(pentafluorophenyl)borane (BCF) as a catalyst. The structural composition of PDMS-b-PEG (PR11) and PEG-b-PDMS-b-PEG (PR12) was corroborated by FTIR, 29Si NMR, and TGA. The BCPs were assembled in an aqueous solution, obtaining micelles between 57 and 87 nm in size. PR11 exhibited a higher (2.0 g L-1) critical micelle concentration (CMC) than PR12 (1.5 g L-1) due to the short chain length. The synthesized nano micelles were used to encapsulate curcumin, which is one of three compounds of turmeric plant 'Curcuma longa' with significant biological activities, including antioxidant, chemoprotective, antibacterial, anti-inflammatory, antiviral, and anti-depressant properties. The encapsulation efficiency of curcumin was 60% for PR11 and 45% for PR12. Regarding the release study, PR11 delivered 53% curcumin after five days under acidic conditions (pH of 1.2) compared to 43% at a pH of 7.4. The degradation products of curcumin were observed under basic conditions and were more stable at acidic pH. In both situations, the release process is carried out by breaking the silyl-ether bond, allowing the release of curcumin. PR11 showed prolonged release times, so it could be used to reduce ingestion times and simultaneously work as a nanocarrier for other hydrophobic drugs.

Copper-Catalyzed Direct Thiolation of Ketones Using Sulfonohydrazides: A Synthetic Route to Benzylic Thioethers

A facile copper-catalyzed sustainable thiolation of ketones with sulfonohydrazides has been designed for the efficient construction of benzylic thioethers in excellent yield under mild reaction conditions. The current approach avoids the widely used thiolation reagent, thiols. The commercial availability of the base and reagents, broad substrate scope, and convenient reaction procedure make it an attractive method for benzylic thioether synthesis.

Boron Lewis Acid Catalysis Enables the Direct Cyanation of Benzyl Alcohols by Means of Isonitrile as Cyanide Source

The development of an efficient and straightforward method for cyanation of alcohols is of great value. However, the cyanation of alcohols always requires toxic cyanide sources. Herein, an unprecedented synthetic application of an isonitrile as a safer cyanide source in B(C₆F₅)₃-catalyzed direct cyanation of alcohols is reported. With this approach, a wide range of valuable α-aryl nitriles was synthesized in good to excellent yields (up to 98%). The reaction can be scaled up and the practicability of this approach is further manifested in the synthesis of an anti-inflammatory drug, naproxen. Moreover, experimental studies were performed to illustrate the reaction mechanism.

Copper-Catalyzed Thiolation of Hydrazones with Sodium Sulfinates: A Straightforward Synthesis of Benzylic Thioethers

A facile and sustainable protocol for the thiolation of hydrazones with sodium sulfinates has been developed in the presence of CuBr₂ and DBU in DMF to afford diverse benzylic thioethers. Control experiments reveal a radical pathway involving a thiyl radical as a key intermediate.

Brønsted Acid-Catalysed Dehydrative Substitution Reactions of Alcohols

The direct, catalytic dehydrative substitution of alcohols is a challenging, yet highly desirable process in the development of more sustainable approaches to organic chemistry. This review outlines recent advances in Brønsted acid-catalysed dehydrative substitution reactions for C-C, C-O, C-N and C-S bond formation. The wide range of processes that are now accessible using simple alcohols as the formal electrophile are highlighted, while current limitations and therefore possible future directions for research are also discussed.

Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis

Kinetic analysis was used as a tool for rational optimization of catalytic direct substitution of alcohols to enable selective formation of ethers, thioethers, and Friedel–Crafts alkylation products using a moisture-tolerant and commercially available Zr complex.