Simonsen Lecture. Cobalt-mediated radical reactions in organic synthesis

Pattenden, Gerald

doi:10.1039/cs9881700361

Cited by 198 publications

(58 citation statements)

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“…Benzyl (1)(2)(3)(4)(5), heteroaromaticmethyl (6-8) and allyl (9)(10)(11) cobaloximes are reacted with disulfonyl chlorides, 4,4 0 -biphenyldisulfonyl chloride (A) and 2,4-mesitylenedisulfonyl chloride (B) in 1:2 molar ratio in dichloromethane at 0°C under anaerobic and photolytic condition. A smooth reaction takes place and is complete within 3 h to give a mixture of products, disulfone, dimer and O-organodimethyl glyoxime (dmgH ether).…”

Section: Resultsmentioning

confidence: 99%

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Reactions of organocobaloximes with aryldisulfonyl chlorides

Gupta¹,

Vijaikanth²

2004

Journal of Organometallic Chemistry

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Section: Resultsmentioning

confidence: 99%

“…There are several type of reactions where cobalt complexes have played a prominent role as stoichiometric reagents or catalysts [2][3][4][5]. In particular the application of organocobaloximes in organic synthesis is well documented in the literature [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Reactions of organocobaloximes with aryldisulfonyl chlorides

Gupta¹,

Vijaikanth²

2004

Journal of Organometallic Chemistry

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“…These versatile organometallic complexes are used in a variety of enzymes to catalyze radical rearrangements and methyltransfers. Moreover, vitamin B12 has found use in organic chemistry for carbon-carbon bond formations [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Vitamin B12: An efficient type catalyst for the one-pot synthesis of 3,4,5-trisubstituted furan-2(5 H )-ones and N -aryl-3-aminodihydropyrrol-2-one-4-carboxylates

Kangani

Maghsoodlou

Hazeri

2016

Chinese Chemical Letters

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“…Vitamin B 12 and its derivatives have received considerable attention for their use in organic chemistry [11][12][13][14][15][16][17][18][19]. The cobalamin cofactor plays an integral role in methyl transfer by donating methyl groups to homocysteine and accepting them from CH 3 -H 4 folate [20][21][22].…”

Section: The Mechanisms Of Methylcobalamin and Adenosylcobalamin Actimentioning

confidence: 99%

“…General, Industrial and Ecological Chemistry. 2016, 11(1), [10][11][12][13][14][15][16][17][18][19][20] Vitamin B 12 is known to participate in at least two types of enzyme-catalyzed reactions [8][9][10] in the human body: a) isomerase rearrangements with participation of the adenosylcobalamin form of vitamin B 12 ; b) methyltransferases with participation of the methylcobalamin form of vitamin B 12 . To date, human consumption of the various vitamin B 12 varieties and their mechanisms of action in the human body are still under study.…”

Section: Introductionmentioning

confidence: 99%

The Nature of the Co-C Bond Cleavage Processes in Methylcob(II)Alamin and Adenosylcob(III)Alamin

Spataru¹,

Fernández²

2016

ChemJMold

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Abstract. Unfortunately, there are still signifi cant disagreements between experimental and theoretical data of rate constants, energy barriers for Co-C bond cleavage process and coordination numbers of vitamin B 12 coenzyme species in spite of the remarkable efforts done by research community. Therefore, no grounded mechanisms for Co-C vitamin B 12 coenzyme bond breaking process and subsequent reactions have been found up to now. The infl uence of the mixing orbitals e.g. Pseudo-Jahn-Teller and similar effects on the reactions paths of bond-cleavage mechanisms of vitamin B 12 co-factors must be taken into account by utilizing multi-reference methods, in particular multiconfi gurational self-consistent fi eld (MCSCF) method. Then, the change in total energy along the normal coordinate Q for the stretching mode including Co-C and Co-N bonds in vitamin B 12 cofactors is expected due to a "vibronic" coupling term, which couples an excited state and ground state by a second order derivative potential-energy operator. The strong state mixing effect is expected to lead to low energy barriers and to Co-C and Co-N axial bond cleavage events in agreement with experimental data. Afterward, the updated mechanisms of vitamin B 12 bio-processes can be determined.Keywords: vitamin B 12 , mechanism, bio-catalysis, Pseudo-Jahn-Teller effect, DFT, MCSCF. Received: December 2015/ Revised fi nal: February 2016/ Accepted: February 2016 IntroductionVitamin B 12 cofactor is one of eight B vitamins and is involved in mammalian cellular metabolism, infl uencing amino acid and DNA synthesis [1] and hematopoiesis. The best known human physiological function of vitamin B 12 is its role in promoting normal health in the brain and nervous system. Vitamin B 12 anemia can cause such neurologic dysfunction as weakness, fatigue, light-headedness, rapid heartbeat, rapid breathing, pale skin color, bruising, and bleeding (including bleeding gums). The more severe vitamin B 12 anemia dysfunctions are characterized by tingling or numbness of the fi ngers and toes, diffi culty walking, mood changes, depression, memory loss, disorientation and, in most severe cases, dementia [2]. Vitamin B 12 defi ciency has even been considered in playing a role in the development of Alzheimer's disease [3][4][5][6][7].The vitamin B 12 cofactor contains a cobalt atom surrounded by an equatorial corrin ring. Covalently linked to the central atom is a dimethylbenzimidazole that occupies one of the axial coordination positions. The opposite coordinate is available for several ligands in bio-medium or in solution; however, known biologically active structures containing adenosyl-or methyl have been considered most often (Figure 1).

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Simonsen Lecture. Cobalt-mediated radical reactions in organic synthesis

Cited by 198 publications

References 0 publications

Reactions of organocobaloximes with aryldisulfonyl chlorides

Reactions of organocobaloximes with aryldisulfonyl chlorides

Vitamin B12: An efficient type catalyst for the one-pot synthesis of 3,4,5-trisubstituted furan-2(5 H )-ones and N -aryl-3-aminodihydropyrrol-2-one-4-carboxylates

The Nature of the Co-C Bond Cleavage Processes in Methylcob(II)Alamin and Adenosylcob(III)Alamin

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