Related Experiment Video
Updated: May 21, 2025

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Merging Ketyl Radical Chemistry and Allylboration via Strain Release: One-Pot Multicomponent Access to Sterically
Aiswarya Mini1, Het Vyas1, Ashvin J Gangani1
1Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.
Abstract:
Ketyl radical-mediated ring opening and [2σ+2π] cycloaddition of cyclopropyl ketones (CPKs) with alkynes typically require activation by alkyl, aryl, or carbonyl groups yielding cyclopentenes having one or two non-adjacent stereocenters. We developed a one-pot multicomponent reaction of diboryl-activated CPKs with alkynes and aldehydes that merges ketyl radical chemistry with allylboration. This method enabled highly diastereoselective access to densely functionalized cyclopentenes featuring homoallylic alcohol, ketone, and alkenyl boronate motifs on adjacent quaternary, tertiary, and secondary stereogenic centers. Additionally, diboryl CPKs also allowed the synthesis of rare ketone-functionalized γ,γ-disubstituted allylic diborons.
Related Concept Videos
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Radical Substitution: Allylic Bromination
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration-Oxidation of Alkenes
Preparation of Alcohols via Addition Reactions
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
Aldol Condensation with β-Diesters: Knoevenagel Condensation

