Stereochemistry of the alkylation of cobalt(I)

Abstract

Analogous products have been obtained from acetone and from 2-butanone in slightly lower yields. In these cases products 2 and 3 (R = CF3)2 from the acetylene and carbon disulfide alone were also obtained.With 2-butanone, alkylation occurred exclusively at the methylene group. Aliphatic aldehydes such as propionaldehyde and isobutyraldehyde gave analogous products in 28 and 29 % yield along with 2 and 3.Dimethyl acetylenedicarboxylate reacted similarly with carbon disulfide and aldehydes and ketones. Slightly higher temperatures (120-140°) were needed and yields have generally been lower. This reaction is not general for compounds with acidic hydrogen. Ethyl malonate and malononitrile were not alkylated. In these cases products 1, 2, and 3 were obtained.

Ein synthetisches Modell für die Aktivstelle der Coenzym‐B12‐abhängigen Methylmalonyl‐CoA‐Mutase

“…Sdp -bis(5,6-dioxoheptyl)ester (7). In einer Tauchfritte wurde eine Losung von 1,2 g (3 mmol) 6 in 45 ml Methanol auf -18" gekiihlt und wahrend 13 Min (lo), 121 (9), 122 (9), 129 ( I I ) , 124 (9), 125 (9), 126 (18) 127 (9), 128 ( S ) , 138 (6), 139 (86), 140 (16), 141 (24), 142 (40), 143 (4), 156 (6), 157 (27), 158 (65), 159 (7), 2181220 (3/3), 367/369 (2/2), 430/432 (l/l), 505 (5), 507 (7), 509 (3), 5221524 (8,5/9,5). (12 (Fig.…”

New Developments in the Field of Vitamin B12: Reactions of the Cobalt Atom in Corrins and in Vitamin B12 Model Compounds

“…Recently, cobaloximes were employed as protecting groups in the synthesis of certain amino acid derivatives [42! This reactions shows some analogy to Wullach's aminomethylation method and can also be performed catalytically. With thiols in place of amines, the corresponding methylthio compounds are obtained, but in this case intermediate organocobaloximes analogous to (20) could not be isolated. A complex of type (20), with R=C6H5, reacts with NO?…”

“…With thiols in place of amines, the corresponding methylthio compounds are obtained, but in this case intermediate organocobaloximes analogous to (20) could not be isolated. A complex of type (20), with R=C6H5, reacts with NO? to yield a compound in which the -CH2-N(NO)-C6H5 residue is attached to cobalt.…”

“…The cobalt(1) supernucleophiles react with conventional alkylating agents to yield organocobalt complexes, the reactions are nucleophilic substitutions and occur with inversion at the a-carbon atom [20]. Epoxides and certain cyclopropane derivatives also react with the cobalt(1) chelates.…”

Cob(I)alamin als Katalysator. 6. Mitteilung [1]. Bildung und Fragmentierung von Alkylcobalaminen, ein Gleichgewichtsprozess zwischen nukleophiler Addition und reduktiver Fragmentierung

“…-Alkylcobalamine, gut bekannte organometallische Verbindungen, die auch in der Natur in Form von Methylcobalamin [2] [3] und Coenzym BI2 [4] vertreten sind, werden oft durch Angriff des stark nukleophilen [5] @-Cob-(1)alamins') an elektrophilen C-Zentren hergestellt [5] [ 1 1-13]*). Reaktionsmechanistisch sind Sub~titutionen~) von Abgangsgruppen [ 121 [16][17][18][19][20][21][22][23][24], Elektronen-Transfer-Reaktionen [ 121 [25] [26], Anlagerungen an die Doppelbindung von Acrylsystemen [2 11 [27], Offnung von Epoxiden, Athylenimin und Tetrahydrofuran [2 11 [22] [28] [29] sowie Anlagerungen an isolierte Dreifachbindungen [2 11 mehrfach beschrieben. Wenig hingegen wurde uber die Addition an isolierte Doppelbindungen veroffentlicht.…”