A one-pot conversion of olefins to .alpha.,.beta.-unsaturated carbonyl compounds. An easy synthesis of 2-cyclopentenone and related compounds

Abstract

There are few compounds that have more potential and versatility in organic synthesis than 2-cyclopentenone1 and its higher homologues. Yet the available sources of these materials are generally tedious, multistep synthetic routes2 or expensive commercial suppliers.3 A conceptually attractive synthetic entry to this general class of compounds lies in the direct conversion of their parent olefins4 through an allylic oxidation pathway. While an impressive amount of research has demonstrated the utility of such a strategem with a variety of substrates,46 no approach has been generally applicable to the simple C-5 through C-8 cycloalkenes. We now report an exceedingly efficient, one-pot synthesis of the 2-cycloalkenones and other ,/3-unsaturated carbonyl compounds by an in situ photooxygenation-elimination procedure.

Radical clocks as probes of 1,4-biradical intermediates in the photochemical cycloaddition reactions of 2-cyclopentenone with alkenes

“…Cyclopentenone was prepared from singlet oxygen oxidation of cyclopentene using the method of Mihelich and Eickhoff (22). Vinylcyclopropane was most conveniently prepared in larger quantities by Bamford Stevens reaction of the tosyl hydrazone of cyclopropyl methyl ketone using a modification of a method described by Kirmse et al (23) as outline below.…”

Isolongifolenone: A Novel Sesquiterpene Repellent of Ticks and Mosquitoes

“…The previous methods of obtaining isolongifolenone from turpentine oil (Ranganathan et al 1970, Pickenhagen andSchatkowski 2004) were inefÞcient (Dauben et al 1969, Lala and Hall 1970, Mihelich and Eickhoff 1983, McQuillin and Wood 1997 and produced many unwanted by-products (Prahlad et al 1964, Shieh et al 1978, Foricher et al 1991, Pickenhagen and Schatkowski 2004. We developed a facile and efÞcient method Zhang 2008, Zhang et al 2008) gifolene, which is commercially available as a feedstock in kilogram to ton quantities.…”

Straightforward Synthesis of a Fluorous Tetraarylporphyrin: an Efficient and Recyclable Sensitizer for Photooxygenation Reactions

“…[29] As expected on the basis of steric considerations, the photooxygenation of (À)-nopadiene 9 [30] (entry 7) afforded the exocycloadduct 10, not yet described in the literature, as the sole product. Finally, cyclopentadiene dimer 11 (entry 9) was reacted in the presence of acetic anhydride and pyridine, according to the protocol established by Mihelich and Eickoff, [31] to give the corresponding a,b-unsaturated ketone 12. This reaction required the use of CH 2 Cl 2 as solvent, in fact, photooxygenation failed to furnish the desired product when run in the less polar CCl 4 .…”