Direct and Stereoselective Alkylation of Nitro Derivatives with Activated Alcohols in Trifluoroethanol

Copper-Catalyzed Propargylation of Nitroalkanes

Using a commercially available, inexpensive, and abundant copper catalyst system, an efficient α-functionalization of nitroalkanes with propargyl bromides is now established. This mild and robust method is highly functional group tolerant and provides straightforward access to complex secondary and tertiary homopropargylic nitroalkanes. Moreover, the utility of these α-propargylated nitroalkanes is demonstrated through downstream functionalization to biologically relevant, five-membered N-heterocycles such as pyrroles and 2-pyrrolines.

Catalytic Friedel-Crafts Reactions of Highly Electronically Deactivated Benzylic Alcohols

Highly electronically deactivated benzylic alcohols, including those with a CF₃ group adjacent to the OH-bearing carbon, undergo dehydrative Friedel-Crafts reactions upon exposure to catalytic Brønsted acid in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solvent. Titration and kinetic experiments support the involvement of higher order solvent/acid clusters in catalysis.

Fluorinated alcohol-mediated [4 + 3] cycloaddition reaction of indolyl alcohols with cyclopentadiene

This paper describes a catalyst- and additive-free, [4 + 3] cycloaddition reaction of 3-indolylmethanols with cyclopentadiene in HFIP, producing cyclohepta[b]indole derivatives in high yields and with wide substrate scope.

Highly Diastereoselective Michael Reactions Using β-Nitrocarbonyl Nucleophiles

We have discovered a highly diastereoselective Michael reaction of α-substituted, β-nitrocarbonyl compounds to deliver highly functionalized stereodiads containing fully substituted nitrogen-bearing centers. Good to excellent yields and diastereoselectivities are observed. This transformation is tolerant of various types of carbonyl groups on the nucleophilic partner, as well as a range of unsaturated electrophiles. Mechanistic investigations are consistent with internal hydrogen bonding in the nitroalkane tautomer as the major factor in the control of diastereoselectivity in these transformations.

Intramolecular etherification and polyene cyclization of π-activated alcohols promoted by hot water

Hot water, acting as a mildly acidic catalyst, efficiently promoted intramolecular direct nucleophilic substitution reactions of unsaturated alcohols with heteroatom or carbon nucleophiles. In a mixed solvent of water and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), polyene cyclizations using allylic alcohols as initiators gave the desired cyclized products, and in neat HFIP, a tricyclization reaction gave a tetracyclic product in 51% chemical yield.