Semester

Fall

Date of Graduation

2013

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Xiaodong Michael Shi

Committee Co-Chair

Peter M. Gannett

Committee Member

Jeffrey L. Petersen

Committee Member

Bjorn C. G. Soderberg

Committee Member

Kung K. Wang

Abstract

Amine Nucleophilic Addition to Nitro-alkene as a New Reaction Mode for the Synthesis of N-heterocycles: An efficient stereoselective synthesis of polycyclic lactams has been developed using Michael addition of conjugated amino-esters to nitro-alkenes. Using acyclic and cyclic aminoesters, this method provided a promising approach to the synthesis of bicyclic and tricyclic lactam core (5,5; 6,5; 5,5,5; 5,6,5; 6,5,5; 6,6,5 etc) in moderate to excellent yield (up to 95%) and excellent diastereoselectivities (up to 99:1 dr). The key steps in this asymmetric synthesis include a heteroatom Michael-Michael addition followed by reductive amidation to gamma-lactams. Lactam cores are biologically active broad spectrum antibiotics.;Enantioselective Synthesis of Piperidines by Exocyclic Chirality Transfer: Piperidines are very important structural moieties contained in a wide range of biologically active and medicinally significant compounds. An efficient route to chiral piperidines was developed which involved diastereoselective synthesis of substituted piperidines (yields up to 75% with dr up to 10:1 of single isomer) followed by removal of one chiral fragment also called N-deprotection to enantiopure piperidine (yields up to 92%) with 100% chirality retention.;Unique Reactivity of Triazole Gold towards Alkyne Activation to Enones and Chiral Allenes: 1,2,3-Triazole coordinated gold(I) complexes were found as the effective catalysts in promoting propargylic ester/ether rearrangement and sequential allene hydration giving enones with excellent yields (up to 97% yields, 0.2% catalyst loading). This catalyst also catalyzed the more challenging Meyer-Schuster rearrangement (0.5% catalyst loading, up to 98% yields). Unlike other reported Au catalysts, the TA-Au complexes provided effective chirality transfer without racemization over a long period of time, giving enantioriched allenes with excellent stereoselectivity (1% catalyst loading, up to 99% ee).

Download

Share

COinS