5-Endo Trig Oxidative Radical Cyclizations of Ugi-3CR Products toward 1,4-Imidazolidinones

Abstract

A 5-endo trig oxidative radical cyclization of benzylamine-derived Ugi three-component reaction products rapidly affords imidazolidinones with three diversity elements. This adaptation of our previously described multicomponent reaction− oxidation methodology further showcases manipulation of the diversity elements in multicomponent reaction products via oxidative radical cyclizations, which generates highly decorated privileged heterocycles.

Visible-Light-Induced Oxazoline Formations from N-Vinyl Amides Catalyzed by an Ion-Pair Charge-Transfer Complex

“…In the polar solvent methanol, the contact ion pair, assured by a large amount of TBAI, is excited to its singlet excited state ( 1* PI ) under blue LED irradiation, which undergoes ISC to the triplet excited state ( 3* PI ), wherein the phenanthridinyl and iodine radical pair is formed . Single-electron oxidation of a1 by iodine radical produces radical cation species I which later proceeds with a 5- endo-trig radical cyclization, subsequently releasing a proton to provide the oxazoline radical II . The I – is oxidized by 1 O 2 (generated from 3 O 2 in the air via energy transfer with 3* PI ) to form the molecule iodine I 2 , which then traps the radical II to generate 4-iodo-2-phenyl-4,5-dihydrooxazole intermediate III (detected by HRMS).…”

Six‐Component Reactions and Beyond: The Nuts and Bolts

“…In addition to the Ugi reaction, a battery of MCRs are available in the tool box of the modern day chemist namely Petasis, Povarov and Groebke‐Blackburn‐Bienaymé reactions to name but a few [44–46] . Indeed, it must be noted that the discovery of each new MCR often spawns efforts from prominent chemists drawn on these named reactions to shorten and create a novel synthetic routes [47–52] . Shown in Figure 1 is various types of well‐known named MCRs.…”

“…[44][45][46] Indeed, it must be noted that the discovery of each new MCR often spawns efforts from prominent chemists drawn on these named reactions to shorten and create a novel synthetic routes. [47][48][49][50][51][52] Shown in Figure 1 is various types of well-known named MCRs.…”

New Efficient Synthesis of 6,12-Dihydro-5H-quinazolino[3,2-a] quinazolin-5-ones via Ugi/Staudinger/Aza-Wittig/Addition/Nucleophilic Acyl Substitution Sequence

“…18,19 Recently the sequence of Ugi reaction, followed by other organic reactions, has been utilized successfully in the synthesis of a series of biologically useful heterocycles. [20][21][22][23][24][25][26][27][28] For example, the spirocyclic pyrrol-2-one dienones were prepared diastereoselectively by Ugi and gold-catalyzed ipso-cyclization. 20 Diverse imidazolidinone scaffolds were obtained successfully by sequential Ugi-3CR and 5-endo-trig oxidative radical cyclization.…”