Synthetic Studies on Insect Hormones. IX. Stereoselective Total Synthesis of a Racemic Boll Weevil Phermomone

Abstract

Recent isolation3 of the sex attractant of the male boll weevil (Anthonomus granáis Boheman) followed a most difficult phase of insect pheromone research4 and allowed structure elucidation4 of the essential components as the monoterpenes 1, 2, and 3 or 4, which have recently been synthesized by nonselective routes.5

Stereoselective Intermolecular [2 + 2]-Photocycloaddition Reactions and Their Application in Synthesis

“…Photochemical approaches to this molecule center on the construction of the cyclobutane ring by photocycloaddition of a cyclic alkenone to ethene (Scheme 19). 44,69,71,100 induced diastereoselection was discussed earlier and they were transformed to grandisol.…”

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

“…[266] Sehr viel glatter verliefen die Enon-Photocycloadditionen von Ethylen an 3-Methylcyclopent-2-enon (zu 196) [267] und an 3-Methylcyclohex-2-enon (zu 197). [268] Das racemische Intermediat 196 wurde auch für einen enantioselektiven Zugang zu (+)-Grandisol (73) über eine kinetische Racematspaltung genutzt. [269] Vorstufen für die Produkte 198 [270] und 199 [271] waren das entsprechende Lacton (Acetophenon als Sensibilisator) und der entsprechende Ketoester.…”

Corrosion News

“…The research group that discovered grandisol ( 73 ) was the first to complete its synthesis by a photochemical approach, by using a very unselective intermolecular [2+2] photocycloaddition to generate intermediate 195 266. The enone photocycloadditions of ethylene to 3‐methylcyclopent‐2‐enone267 or 3‐methylcyclohex‐2‐enone268 proceeded more efficiently to afford cyclobutanes 196 or 197 . The racemic intermediate 196 was also used to achieve an enantioselective synthesis of (+)‐grandisol ( 73 ) by kinetic resolution 269.…”