Stereoselective Synthesis of Sulfones and Amino Acids from Functionalized Heterocycles

Identifier:  TDX:2979

Handle: https://hdl.handle.net/20.500.11797/TDX2979

Authors:  Gómez Pulido, José Enrique

Abstract:
The main goal of this thesis is the development of new stereo- and enantio-selective catalytic methodologies taking advantage of the intrinsic reactivity of functionalized cyclic carbonates and related heterocycles (e.g., nonstrained lactones) and use them as starting materials for the synthesis of more complex chiral organic targets, by means of transition-metal (TM) catalysis (specifically Pd and Cu).Three main research projects are collected in this thesis. In the first project, a new methodology aiming at the stereoselective synthesis of highly functionalized (Z)-configured allylic thioethers and their corresponding sulfones has been developed. This protocol based on a Pd-catalyzed thiolation of vinyl cyclic carbonate substrates features good yields and high (Z)-selectivity. Although effective methodologies for the synthesis of allylic thioether/sulfones are well stablished, a general catalytic methodology for the stereoselective synthesis of (Z)-configured tri- and tetra-substituted allylic thioethers/sulfones remained previously elusive. Our newly developed procedure therefore offers complementary synthetic potential. The second project, describes the first asymmetric synthesis of tertiary propargylic sulfones. These building blocks are of significant importance in organic synthesis and medicinal chemistry. The recently introduced alkyne-functionalized cyclic organic carbonates inspired us to pursue a Cu-catalyzed asymmetric propargylic sulfonylation reaction of these precursors by using versatile sulfinate salts. This practical method provided a new approach targeting the construction of sulfur-containing, tetrasubstituted carbon stereocenters featuring high enantioselectivity and wide functional group diversity. The applicability of the transformation was demonstrated by various functionalization reactions of the tertiary sulfone building blocks. Finally, the last project shows the discovery of a new protocol that enables the efficient assembly of biologically relevant gamma-amino acids bearing quaternary stereocenters. Notably, in this project we took advantage of the catalytic formation of copper-allenylidene intermediates that can be intercepted by a series of amine nucleophiles in an enantioselective fashion allowing the ring opening aminolysis of minimally strained, alkyne-substituted lactones.