Related Experiment Video
Updated: Jun 20, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Formal [4 + 2] cycloaddition of donor-acceptor cyclobutanes and aldehydes: stereoselective access to substituted
Andrew T Parsons1, Jeffrey S Johnson
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Abstract:
A highly diastereoselective synthesis of 2,6-cis-disubstituted tetrahydropyrans (THPs) via Lewis acid-catalyzed formal [4 + 2] cycloaddition of donor-acceptor cyclobutanes and aldehydes has been developed. THP products are formed in up to 96% yield and 99:1 diastereoselectivity. Aromatic, cinnamyl, and aliphatic aldehydes are competent dipolarophiles in this system. This methodology was extended to a [[2 + 2] + 2] cycloaddition of 4-methoxystyrene, dimethyl methylidene malonate, and an aldehyde to furnish THPs directly without prior isolation of the cyclobutane.
Related Concept Videos
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Cycloaddition Reactions: Overview
Cycloaddition Reactions: MO Requirements for Thermal Activation
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
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.
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
