Powerful CarbonCarbon Bond Forming Reactions Based on a Novel Radical Exchange Process

Abstract

Xanthates and related derivatives have proved to be extremely useful for both inter- and intramolecular radical additions. The broad applicability of the intermolecular addition to un-activated olefins opens tremendous opportunities for synthesis, since various functional groups can be brought together under mild conditions and complex structures can be rapidly assembled. The presence of the xanthate in the product is also a powerful asset for further modifications, by both radical and non-radical pathways. Of special importance is the access to highly substituted aromatic and heteroaromatic derivatives and the synthesis of block polymers through a controlled radical polymerisation mediated by various thiocarbonylthio group containing agents (RAFT and MADIX processes).

Living Radical Polymerization by the RAFT Process - A Second Update

“…The past 2 years has seen the publication of further general reviews detailing the RAFT process which include works by Moad, Rizzardo, and Thang, [9][10][11][12] a Handbook of RAFT Polymerization, [13] and a highlight article by Barner-Kowollik and Perrier [14] on the future of RAFT. Reviews on specific areas include the kinetics and mechanism of RAFT polymerization, [15][16][17][18] the use of RAFT to probe the kinetics of radical polymerization, [19,20] the use of RAFT in organic synthesis, [21] amphiphilic block copolymer synthesis, [22,23] the synthesis of end functional polymers, [24] the synthesis of star polymers and other complex architectures, [25,26] the use of trithiocarbonate RAFT agents, [27] the use of xanthate RAFT agents (MADIX), [28] polymerization in heterogeneous media, [29][30][31][32] RAFT polymerization initiated with ionizing radiation, [33] polymer synthesis in aqueous solution, [34][35][36][37] surface and particle modification, [38,39] synthesis of self assembling and/or stimuli responsive polymers, [36,40] RAFT-synthesized polymers in drug delivery, [22,41] and other applications of RAFTsynthesized polymers. [30,42,43] The process is also given substantial coverage in most recent reviews that, in part, relate to polymer synthesis, living or controlled polymerization, or novel architectures.…”

Some aspects of radical cascade and relay reactions

“…Since its discovery, at least 2000 additions employing over 200 different xanthates have been reported. One example of sequential intermolecular and intramolecular reactions pitting together β-pinene 61 and bis-xanthate 62 is shown in scheme 10 [32]. The first step involves radical addition to the exocylic alkene with concomitant opening of the cyclobutane ring to give intermediate 63.…”

Unusual Kinematics‐Driven Chemistry: Cleaving CH but Not COOH Bonds with Hyperthermal Protons To Synthesize Tailor‐Made Molecular Films

“…Driven by these demands, various molecular layers with specific chemical functionalities have been developed by a number of innovative chemical synthetic approaches that include, for example, forming carbon-carbon bonds by taking advantage of xanthates and related derivatives; [3] the application of organo-lithium compounds containing protected functional groups; [4] polymer grafting of molecular segments that have the required functionalities; [5] and addition of self-assembled monolayer (SAM) molecules with appropriate tail groups. [6] Although the latter approach gives precise control of molecAbstract: Unconventional reactiondesign strategies have been developed to exploit the intriguing kinematics that occur when adsorbed organic molecules are bombarded by a beam of hyperthermal protons: kinematic energy transfer is only effective in H!H collisions and thus only C À H bonds are cleaved.…”