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Diastereoselective Piperidine Synthesis through DDQ-Mediated Oxidative Cyclization of Enamides, N-Vinyl Carbamates, and N-Vinyl Sulfonamides

Brizgys, Gediminas J. (2011) Diastereoselective Piperidine Synthesis through DDQ-Mediated Oxidative Cyclization of Enamides, N-Vinyl Carbamates, and N-Vinyl Sulfonamides. Master's Thesis, University of Pittsburgh. (Unpublished)

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The DDQ-mediated oxidative cyclization chemistry that was previously developed in our group for the synthesis of tetrahydropyrones from allylic and benzylic ethers has been expanded for use with enamides, N-vinyl carbamates, and N-vinyl sulfonamides to synthesize piperidine rings. This chemistry provides a new oxidative method to generate N-acyliminium and N-sulfonyliminium ions. Cyclization onto the oxidatively generated α,β-unsaturated N-acyliminium and N-sulfonyliminium ions has been performed with a variety of tethered nucleophiles. The cyclization reaction suffers no difficulties in regards to chemoselectivity or over oxidation. Moreover, the resulting unit of unsaturation in the products provides an additional synthetic handle not generated through more classical iminium ion chemistry. Significantly, stereocontrol in the reaction was achieved through the use of (E)- and (Z)-allylsilanes and silyl enol ethers. Transition state models were formulated through information obtained from studies of monocyclic and bicyclic compounds synthesized through the oxidative cyclization reaction. Finally, the reaction was made catalytic through regeneration of DDQ via oxidation of the DDQ byproduct by Mn(OAc)3. This chemistry provides a powerful new method for generating nitrogen heterocycles and will provide new ways of accessing alkaloids.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Brizgys, Gediminas J.gjb11@pitt.eduGJB11
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFloreancig, Paul Eflorean@pitt.eduFLOREAN
Committee MemberWilcox, Craig Sdaylite@pitt.eduDAYLITE
Committee MemberCurran, Dennis Pcurran@pitt.eduCURRAN
Date: 14 September 2011
Date Type: Completion
Defense Date: 1 August 2011
Approval Date: 14 September 2011
Submission Date: 4 August 2011
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Acyliminium; Cyclization; DDQ; N-Acyliminium; N-Sulfonyliminium; Oxidation; Piperidine; Sulfonyliminium
Other ID:, etd-08042011-143144
Date Deposited: 10 Nov 2011 19:57
Last Modified: 15 Nov 2016 13:48


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