A stereoselective approach in preparation of γ-lactam precursors for oxazolomycin's synthesis. Issue 15 (10th April 2020)

• Record Type: Journal Article
• Authors: Oleksak, Patrik; Gonda, Jozef; Imrich, Jan; Malinak, David; Lycka, Antonin; Musilek, Kamil
• Is Part Of: Tetrahedron. Volume 76:Issue 15(2020)
• Publication Date: 2020-04-10
• Subjects: Oxazolomycin -- Pyroglutamate core -- Gama-lactam -- Stereoselective synthesis; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2020.131111
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: A stereoselective approach to C-3′ methyl attached γ-lactam derivatives as the precursors of pyroglutamate core of oxazolomycins is described. The synthesis started from d -xylose and utilized [3, 3]-heterosigmatropic rearrangement. The key lactamization was achieved with intramolecular aldol reaction and ring-closing metathesis. The accomplished stereoselective aldol cyclization was elucidated with Zimmerman-Traxler transition state models. Stereoselectivity of the aldol reaction was explained as a consequence of chelation and bridgehead atoms linkage. The present work also encompasses proposed structures of ( E )- and ( Z )- generated enolates during intramolecular aldol reaction. Although stereocenters were not formed during ring-closing metathesis, a stereospecific reduction of prepared double bond functionality was successfully accomplished. Graphical abstract: Image 1 Highlights: Synthesis of γ-lactam derivatives as the precursors of pyroglutamate core of oxazolomycins was succesfully accomplished. The key lactamization was achieved with intramolecular aldol reaction and ring-closing metathesis. The stereoselective aldol cyclization was elucidated via Zimmerman-Traxler transition state models.