Ring expansion reactions of PO-containing molecules

Abstract

A series of ring expansion reactions of PO-containing molecules have been developed for the synthesis of medium-sized ring cyclic phosphonate esters and phosphonamidates.

A Modular Strategy for the Synthesis of Macrocycles and Medium-Sized Rings via Cyclization/Ring Expansion Cascade Reactions

“…This manuscript is focused on the development of a general, modular strategy for the synthesis of macrocycles and medium-sized rings that does not require high dilution conditions, using novel cyclization/ring expansion (CRE) cascade reactions. , The concept is illustrated in Scheme B. A key design principle followed in all of the new methods described is to ensure that the cascade proceeds exclusively via low-energy “normal-sized” ring cyclic transition states.…”

Expanding the scope of the successive ring expansion strategy for macrocycle and medium-sized ring synthesis: unreactive and reactive lactams

“…A major focus of our group in recent years has been the development of side-chain insertion type ring expansion reactions, 4 a for the synthesis of medium-sized and macrocyclic lactams, 6 lactones, 7 thiolactones, 8 sulfonamides 9 and phosphonate esters. 10 Within this programme, the development of ‘Successive Ring Expansion’ (SuRE) methods has been a major driver. The general SuRE strategy is summarised in Scheme 1a, which depicts a method for the ring expansion of lactams 1 , via N -acylation ( 1 → 3 , X can be NR, O or S), protecting group cleavage ( 3 → 4 ) and ring expansion ( 4 → 5 ).…”