Transformation of the B Ring to the C Ring of Bryostatins by Csp³–H Amination and Z to E Isomerization

Abstract

An interesting approach to transform the B ring of bryostatins to the C ring has been developed. The key tactics of the approach feature an intramolecular Csp-H bond amination to form spirocyclic hemiaminal, which undergoes ring opening to afford the C ring found in bryostatin 17. The subsequent epoxidation/oxidation sequence results in Z to E isomerization of the exo-cyclic enoate, delivering the common precursor, which could be transformed into the C ring found in bryostatins 1, 2, 4-9, 12, 14, and 15.

Rhodium‐Catalyzed CH Annulation of Nitrones with Alkynes: A Regiospecific Route to Unsymmetrical 2,3‐Diaryl‐Substituted Indoles

“…Well‐established methods exist for the preparation unsymmetrical 2,3‐diaryl‐substituted indoles from prefunctionalized reactants or by multistep procedures 8b,f,i. 11 However, CH functionalization has been demonstrated to be a more versatile and efficient strategy for the synthesis of heterocycles 12.…”

Synthesis and Some Biological Properties of Pyrrolo[1,2‐a]indoles

“…Pyrroloindoles 256 with a yield of 59% were produced upon cyclization of acetylene derivatives of chloraniline 257 with palladium complexes [150,151] (Scheme 80).…”

Rhodium-Catalyzed Nitrene/Alkyne Metathesis: An Enantioselective Process for the Synthesis of N-Heterocycles

“…Catalytic nitrene transfer reaction represents a powerful and direct method for the construction of a C–N bond and has shown broad applications in modern organic synthetic chemistry. , Since the amino species and N -heterocycles are prevalent in naturally occurring molecules and pharmaceutical agents, the development of catalytic selective nitrene transformation has large application potential and has attracted much attention over the past decades . In this context, intensive efforts have been invested exploring a variety of metal catalysts, including Rh, Ru, Ag, Mn, Cu, Co, and Fe .…”