Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

• Nathan J. Gesmundo and
• David A. Nicewicz

Beilstein J. Org. Chem. 2014, 10, 1272–1281, doi:10.3762/bjoc.10.128

• were inspired by the work of Miyashi, who, during the course of the investigation of the cation radical Cope rearrangement, discovered an intriguing endoperoxide-forming reaction (Scheme 1, reaction 1). Upon exposure of 1,5 and 1,6-dienes to catalytic quantities of 9,10-dicyanoanthracene (DCA) under UV

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• the Cope rearrangement, it has to be noted that the preference of transition states (chair/boat) is opposite. Whereas the Cope rearrangement of hexa-1,5-diene 12 usually proceeds through chair-like transition state 12' (see Scheme 2) and not through the energetically disfavoured boat-transition state

• characterization of cis-divinylcyclopropane by Brown. Transition states for the Cope rearrangement and the related DVCPR. Ts = transition state. Two possible mechanisms of trans-cis isomerizations of divinylcyclopropanes. Proposed biosynthesic pathway to ectocarpene (21), an inactive degradation product of a

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• -catalyzed Cope rearrangement through a boat-like transition state would deliver the cis-2,3-disubstituted cycloheptenyl acetates of type 5 (Scheme 3) [43]. Although the process was essentially developed in a racemic fashion, by using Au3/AgSbF6 or a combination of Au4 and (PhO)3PAuSbF6 (Scheme 3), the

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• double oxy-Cope rearrangement), and the resulting 76 subsequently undergoes an electrocylic ring closure to a four-membered ring system. On workup (hydrolysis) a mixture of the cis and trans isomers of 77 is obtained in very good yield (ca. 80%). A conjugated bisallene carrying three diphenylphosphine

• precursors [112]. A radical cation Cope rearrangement of 1,5-hexadiyne (129) to the 1,2,4,5-hexatetraene radical cation was initiated by oxidizing bipropargyl radiolytically in a Freon matrix at 77 K [113]. The 129→2→130 sequence, and in particular its last step, has also been used several times for the

An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III) ions

• Markus Albrecht,
• Olga Osetska,
• Thomas Abel,
• Gebhard Haberhauer and
• Eva Ziegler

Beilstein J. Org. Chem. 2009, 5, No. 78, doi:10.3762/bjoc.5.78

• peptidic scaffold and the final ligand 1a-H3 is obtained in good yield (90%). Successive Cope rearrangement of the spacers to the 5-position of the quinoline moiety is not observed under the chosen reaction conditions. 1H NMR spectra of 4 and 1a-H3 show pronounced differences for the resonances of the 8

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• Cope rearrangement and an intramolecular Diels-Alder reaction. The substrate for the Cope rearrangement was prepared by the merger of two cyclopentene units (Scheme 1). First, the addition of chloro compound 8 [18] to aldehyde 9 [19] occurred smoothly using the CrCl3/LAH system, developed by Hiyama et

• al. [20]. The resultant alcohol was converted to the methyl ether using NaH and MeI. The subsequent Cope rearrangement of 10 occurred at 200 °C via a boat-like transition state [18] to yield 11. The elaboration of this material to 12 involved treatment with singlet oxygen and AcCl [21] to yield α,β