Intramolecular cycloadditions of cyclobutadiene with olefins.
Intramolecular cycloadditions between cyclobutadiene and olefins can provide highly functionalized cyclobutene-containing products. The outcome of the reaction depends on the nature of the tether connecting the two reactive partners in the cycloaddition. Electronically unactivated olefins attached to cyclobutadiene through a three-atom, heteroatom-containing tether yield successfully the desired cycloadducts, whereas the corresponding substrates without a heteroatom linkage or with a longer tether are less prone to undergo the intramolecular cycloaddition. Calculations were used to help uncover some of the factors that influence the course of the cycloaddition. Successful intramolecular reactions usually require either electronic activation of the dienophile, conformational restriction of the tether, or a slower oxidation protocol. In general, a facile intermolecular dimerization of cyclobutadiene is the major process that competes with the intramolecular cycloaddition.
Limanto
John
J
Department of Chemistry, Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, USA.
Tallarico
John A
JA
Porter
James R
JR
Khuong
Kelli S
KS
Houk
K N
KN
Snapper
Marc L
ML
D000475:Alkenes / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000138:chemical synthesis*; D003503:Cyclobutanes / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D013816:Thermodynamics
D000475:Alkenes; D001952:Bridged-Ring Compounds; D003503:Cyclobutanes