Showing papers by "Harold W. Moore published in 1998"

Cyclobutenone-Based Syntheses of Polyquinanes and Bicyclo[6.3.0]undecanes by Tandem Anionic Oxy-Cope Reactions. Total Synthesis of (+/-)-Precapnelladiene.

Abstract: The addition of ethenyllithium derivatives to the carbonyl of dialkyl squarate-derived bicycloheptenones, e.g., 1a and 6a, initiates a low-temperature anion-accelerated oxy-Cope rearrangement to provide polyquinanes by a transannular aldol reaction of the intermediate bicyclo[6.3.0]undecadienone 4. Additional functionality is introduced by alkylation of the enolate 3 resulting from the oxy-Cope rearrangement. Phosphorylation or triflation of enolate 3 provides an entry into the bicyclo[6.3.0]undecane ring system. An application of this new methodology is demonstrated by the total synthesis of the sesquiterpene natural product (+/-)-precapnelladiene from diisopropyl squarate (10 steps, 12%).

Generation and Intramolecular Cyclization of (2-Ethenylphenyl)bisketenes. Synthesis of Benzofuranones.

Abstract: Several new differentially substituted cyclobutenediones 4a-e have been prepared. Their thermal rearrangement to substituted naphthofuranones 5a-d is reported. This rearrangement involves an unprecedented intramolecular cyclization of a reactive bisketene 6, and forms the naphthofuranone system in good yield.