Methylation by methyl vitamin B12

Abstract

OxfoTd OX1 3QR) Sumnmary Methyl vitamin B,, is shown to be capable of transferring methyl groups to HgII, TlIII, PtII, and AuI; two different reaction paths are involved, one of which, with HgII or TPII, is an acid-base reaction while the other is probably an oxidation-reduction reaction for it requires both PtII and PtIv, or AuI and AuIII.

Cyanide‐Bridged Vitamin B12–Cisplatin Conjugates

“…Some metal complexes, for example, [PdCl 4 ] 2À or a mixture of Pt II and Pt IV species, react quite strongly with cobalamins and demethylate methylcobalamin to aquoor chlorocobalamin. [10,11] Interaction of the activated form of cisplatin, cis-[Pt(NH 3 ) 2 2 + binds to N 3 of the dimethylbenzimidazole unit in the B 12 -backloop, yielding an alkylcobalamin base-off form. It also binds to adenosylcobalamin at the N 7 or N 1 position of the nucleoside ligand.…”

Branch-Selective Addition of Unactivated Olefins into Imines and Aldehydes

“…6 Similar alkyl transmetallations have been reported in non-catalytic systems between alkyl−Co(dmgBF 2 ) 2 Py and inorganic nickel, 8 and proposed for bioorganometallic 9 and catalytic processes. 10 This alkyl transfer does not appear limited to nickel: vitamin B12-mimetics (such as Co(salen) derivatives) can undergo alkyl transfer to palladium, 11 rhodium, 12 other cobalt, 13 platinum, 14 gold, 15 chromium, 16 and zinc 17 salts and organometallic species. Yet despite the apparent generality of this transformation, there is a paucity of preparative cross-coupling methods that leverage this reactivity.…”

Branch-Selective Addition of Unactivated Olefins into Imines and Aldehydes

“…The early transition state of radical reactions allows facile formation of sterically hindered unnatural α-amino acids bearing β-quaternary carbons, and reactive groups like free-hydroxyls (13) or two-electron electrophiles such as esters, epoxides, or aldehydes (8, 15, and 17) are tolerated. Complex feedstock terpenes can engage the sulfinylimines to deliver adducts 12, 14, and 15, and even glycans deliver amino esters with good diastereocontrol (16). Comparison of the optical rotation obtained from our reaction to that of t-butyl glycine derivatives shows that sulfinimes with the (S)-configuration affords the (S)-amine whereas the (R)-sulfinime affords the (R)-amine.…”

“…7,7 Similar alkyl transmetallations have been reported in noncatalytic systems between alkyl-Co(dmgBF2)2Py2 and inorganic nickel, 9 and proposed for bioorganometallic 10 and catalytic processes. 11 This alkyl transfer does not appear limited to nickel: vitamin B12-mimetics (such as Co(salen) derivatives) can undergo alkyl transfer to palladium, 12 rhodium, 13 other cobalt, 14 platinum, 15 gold, 16 chromium, 17 and zinc 18 salts and organometallics species. Yet despite the apparent generality of this transformation, there is a paucity of preparative cross-coupling methods which leverage this reactivity.…”