Non-stabilized diazoalkane synthesis via the oxidation of free hydrazones by iodosylbenzene and application in in situ MIRC cyclopropanation

Abstract

Highly reactive non-stabilized diazo compounds are generated from free hydrazones using iodosylbenzene. In situ MIRC cyclopropanations were performed on a wide array of substrates.

Cobalt Catalyzed Reductive Spirocyclopropanation Reactions

“…An alternative disconnection that could be considered is the addition of a cyclic carbene to an alkene. Recently, Charette demonstrated the generation of sensitive diazocycloalkanes in flow reactors and their uncatalyzed addition to α,β‐unsaturated esters …”

“…In this vein, spirocyclopropanes [3] combine a unique three-dimensional architecture with conformational rigidity, thus representing high-value targets for the development of new synthetic methods. [7] A conceptually straightforward route to spirocyclopropanes would be through a SimmonsÀ Smith-like process using a metal carbenoid reagent derived from a 1,1-dihalocycloalkane ( Figure 1). [5,6] An alterna-tive disconnection that could be considered is the addition of a cyclic carbene to an alkene.…”

“…[5,6] An alterna-tive disconnection that could be considered is the addition of a cyclic carbene to an alkene. Spirocyclopropanations of α,β unsaturated esters using diazocycloalkanes, [7] and catalytic reductive spirocyclopropanations using 1,1-dichlorocycloalkanes. [7] A conceptually straightforward route to spirocyclopropanes would be through a SimmonsÀ Smith-like process using a metal carbenoid reagent derived from a 1,1-dihalocycloalkane ( Figure 1).…”

“…Recently, Charette demonstrated the generation of sensitive diazocycloalkanes in flow reactors and their uncatalyzed addition to α,β-unsaturated esters. [7] A conceptually straightforward route to spirocyclopropanes would be through a SimmonsÀ Smith-like process using a metal carbenoid reagent derived from a 1,1-dihalocycloalkane ( Figure 1). One impediment to realizing such a reaction is that there are no general methods available to prepare 1,1-diiodocycloalkanes.…”

“…Spirocyclopropanes in natural products and pharmaceutical compounds. Spirocyclopropanations of α,β unsaturated esters using diazocycloalkanes, [7] and catalytic reductive spirocyclopropanations using 1,1-dichlorocycloalkanes. 1,1-Dichloro analogs are more accessible but do not react directly with Zn or Et 2 Zn to form metal carbenoids.…”