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Full-Text Articles in Physical Sciences and Mathematics
Asymmetric Synthesis Of All-Carbon Α-Aryl Quaternary Carbonyl Compounds By Palladium-Catalyzed Asymmetric Allylic Alkylation (Pd-Aaa) And Their Application To The Synthesis Of Biologically Important 3,3′-Disubstituted Oxindole And Α-Disubstituted Quaternary Β-Lactone Frameworks, Md. Sharif Al Asad
Theses and Dissertations
The development of catalytic, enantioselective methods for the construction of all-carbon quaternary stereocenters is an outstanding achievement in the recent history of organic chemistry. The palladium-catalyzed asymmetric allylic alkylation (Pd-AAA) reaction has played a key role in creating such stereocenters and has allowed researchers to synthesize a vast number of biologically potent natural products. However, synthetic methodologies to access compounds containing α-aryl groups to the quaternary carbon stereocenters are still rare. The increasing appearance of these all-carbon α-aryl quaternary stereocenters in a growing number of biologically active natural products and pharmaceutical agents creates a pressing need for the ability to …
I. Palladium (0)-Catalyzed Asymmetric Rearrangement Of Allyl Enol Ether For The Synthesis Of Α -Aryl Quaternary Carbon Center. Ii. Synthesis Of Chiral Tryptophan Analogs And Studies Towards Synthesis Of Tryprostatin A And B, Md Nazim Uddin
Theses and Dissertations
The development of efficient catalytic enantioselective synthesis of all carbon quaternary centers is a significant challenge in chemical synthesis due to the difficulties of carbon-carbon bond formation at quaternary center. Using phase transfer catalyst we attempted to create quaternary carbon center via direct C-alkylation of hydroxyarylacrylates, instead we obtained O-alkylated acrylates. We succeeded in C-alkylation which involves an indirect method via the O-alkylation of 3-hydroxy aryl acrylates and a subsequent [3, 3] sigmatropic rearrangement (Claisen rearrangement). The O-alkylated products are obtained in yields ranging from 65-85%, and the corresponding Claisen rearrangement products in yields ranging from 55-90%. Typically Pd(II) catalysts …