Iron-Mediated Radical Nitro-Cyclization Reaction of 1,6-Dienes

Abstract

Sequential steps that involved radical addition of a nitro group to 1,6-dienes promoted by the thermal decomposition of iron nitrate(III) nonahydrate, cyclization, and trapping of the resulting terminal radicals by a chlorine atom in the presence of chloride salt afforded five-membered-ring compounds. The present reaction provides a practical method for the synthesis of nitro compounds due to its simple experimental procedure and its use of nontoxic and inexpensive iron reagents.

Formal Alkylation of Allenes through Highly Selective Radical Cyclizations of Allene‐enes

“…Disappointingly, some typical radical initiators such as Et 3 B, [9] AIBN, [10] and zinc powder [8] failed to catalyze the cyclization reaction of the allene-ene 6 a with 5 a [Eqs. (1) and (2)(3)(4)(5)], which is different from what has been previously reported. Gladly, we found that the radical addition reaction of the allene-ene 6 a with 5 a was indeed be promoted by 50 mol % of zinc powder in the presence of 20 mol % HOAc at 40 8C, thus forming two products exclusively.…”

Iron(III)/NaBH4-Mediated Additions to Unactivated Alkenes: Synthesis of Novel 20′-Vinblastine Analogues

“…In the presence of NaN 3 , the cyclized product 4 was observed in a 25% yield, along with byproduct 5 (32%). 16 No product arising from simple addition to the alkene was observed. Additionally, both the hydroazidation and oxidation of indene using NaBD 4 were found to be non-diastereospecific (Scheme 1).…”

Formal Alkylation of Allenes through Highly Selective Radical Cyclizations of Allene‐enes

“…[1] However, the radical reactions of allenes are largely unknown. [2,3] Particularly, in contrast to the radical cyclization reactions of dienes [4] and enynes, [4k-m, 5] the inter-and intramolecular tandem radical addition/cyclization reactions of allene-enes [6] has not been extensively explored. All the reported reactions proceed in an "allene-to-alkene" fashion, [6] which is consistent with the traditional notion that allenes are more reactive than alkenes towards radicals (Scheme 1).…”