179076-91-6Relevant academic research and scientific papers
Stereoselective Synthesis of the Core Structures of Pyrrocidines and Wortmannines through the Excited-State Nazarov Reactions
Xue, Dongsheng,Que, Yonglei,Shao, Hao,He, Haibing,Zhao, Xiaoli,Gao, Shuanhu
, p. 2736 - 2741 (2021/05/05)
The reaction conditions and scope of the excited-state Nazarov reaction of dicyclicvinyl ketones were studied. The stereochemistry of this electrocyclization is consistent with the mechanism of the pericyclic reaction and Woodward-Hoffmann rule. UV-light-promoted excited-state Nazarov reactions gave hydrofluorenones bearing a syn-cis configuration via a disrotatory cyclization. The core tricyclic hydrofluorenones of pyrrocidines and wortmannines were constructed via the excited-state Nazarov reactions, which demonstrated their synthetic potential in complex natural product total synthesis.
Stereoselective benzannulations and cyclohexadienone annulations of Fischer carbene complexes in the synthesis of decala-2,4-dien-1-ones and in the synthesis of tetralin chromium tricarbonyl complexes
Hsung, Richard P.,Wulff, William D.,Challener, Cynthia A.
, p. 773 - 789 (2007/10/03)
The first general study is reported on the stereoselectivity of the benzannulation reaction involving diastereoselection at the planar center of chirality of the newly formed arene ring complexed to chromium that is induced from a chiral carbon center on the carbene complex. The stereochemistry of a number of 5- and 8-substituted tetralin chromium tricarbonyl complexes, which are produced from the benzannulations of cyclohexenyl carbene complexes with chiral centers at the 3- and 6-positions, is determined. These results are compared with the stereochemistry of the formation of 5,9- and 8,9-disubstituted decala-2,4-dien-1-ones produced from the reactions of the same carbene complexes bearing an additional substituent in the 2-position of the cyclohexenyl ring. The benzannulation reaction is most selective with 3-substituted cyclohexenyl carbene complexes giving predominately the anti-isomer of the 8-substituted tetralin chromium tricarbonyl complexes. In contrast, the cyclohexadienone annulation is most selective with 6-substituted cyclohexenyl carbene complexes giving predominately the trans-isomer of the 5,9-disubstituted decala-2,4-dien-1-ones. A mechanistic accounting of the stereochemical results is proposed which is predicated on three assumptions: 1) that the η1,η3-vinyl carbene complexed intermediate is in equilibrium, 2) vinyl ketene complex formation is irreversible and occurs with a carbon monoxide migration that is in concert with coordination of the double bond of the cyclohexene ring, and 3) the electrocyclic ring closure of the vinyl ketene complex is stereospecific.
Impact of substituent modifications on the atropselectivity characteristics of an anionic oxy-Cope ring expansion
Raquette, Leo A.,Combrink, Keith D.,Elmore, Steven W.,Rogers, Robin D.
, p. 1335 - 1344 (2007/10/02)
The phenomenon of atropisomerism is critically examined in the tricyclic E,syn,up enolates derived from anionic oxy-Cope rearrangement of 1-vinyl-2-cyclohexenyl-7,7-dimethyl-exo-norbornan-2-ols, as well as the ketones derived from their protonation and me
