Friedel-Crafts Alkylation with Carbenium Ions Generated by Electrochemical Oxidation of Stannylmethyl Ethers

Electrifying Friedel-Crafts Intramolecular Alkylation toward 1,1-Disubstituted Tetrahydronaphthalenes

In this work, we successfully employed electrochemical conditions to promote a Hofer-Moest, intramolecular Friedel-Crafts alkylation sequence. The reaction proceeds under mild conditions, employing carboxylic acids as starting materials. Notably, the electrochemical process performed in batch was adapted to a continuous flow electrolysis apparatus to provide a significant improvement. This catalyst-free, electrochemical approach produces an array of tetrahydronaphthalenes that could be used for API synthesis.

HFIP in Organic Synthesis

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

Direct activation of alcohols via perrhenate ester formation for an intramolecular dehydrative Friedel–Crafts reaction

A general and highly efficient intramolecular dehydrative Friedel–Crafts reactions via Re2O7 mediated hydroxyl group activation is described for the syntheses of tetrahydronaphthalene, tetrahydroquinoline, tetrahydroisoquinoline, chromane, and isochromane derivatives.