Side Chain Entropy and the Activation of Organocobalamins for Carbon-Cobalt Bond Homolysis: Synthesis, Characterization, and Thermolysis of the Neopentyl Derivative of a Unique Cobalamin Analog Lacking a c Side Chain

Inorganic Chemistry
Kenneth L. BrownEdward J. Valente


Hydrodeamination of the c-amino derivative, 5, of cyanocobalamin (CNCbl) with hydroxylamine-O-sulfonic acid in aqueous base leads to an extensively rearranged product instead of the c side chain truncated derivative, 1, expected from simple deamination. The rearranged product (CNCbl-8-butanamide) crystallizes in the orthorhombic system, space group P2(1)2(1)2(1) with unit cell dimensions a = 16.041(11), b = 21.94(2), and c = 25.43(2) Å. It is devoid of substituents at corrin ring C(7) but quarternized at C(8) with an "upwardly" pseudoaxial methyl group and a d side chain expanded by one methylene group to a butanamide. The corrin ring of this rearranged derivative is significantly flatter (corrin ring fold angle 9.9 degrees ) than CNCbl itself (fold angle 18.0 degrees ). Conversion of CNCbl-8-butanamide to its neopentyl derivative (NpCbl-8-butanamide), a NpCbl analog which lacks a c acetamide side chain, permits a quantitative assessment of the influence of thermal motions of the c side chain on the entropy of activation for carbon-cobalt bond thermal homolysis in NpCbl. NpCbl-8-butanamide is shown to thermolyze homolytically to give products derived from the Np(*) radical quantitatively. The kinetics of the thermolysis of NpCb...Continue Reading

Related Concepts

hydroxylamine-O-sulfonic acid
Vitamin B 12
Methyl Group
Aqueous solution

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Synapse Loss as Therapeutic Target in MS

As we age, the number of synapses present in the human brain starts to decline, but in neurodegenerative diseases this occurs at an accelerated rate. In MS, it has been shown that there is a reduction in synaptic density, which presents a potential target for treatment. Here is the latest research on synapse loss as a therapeutic target in MS.

Artificial Intelligence in Cardiac Imaging

Artificial intelligence (ai) techniques are increasingly applied to cardiovascular (cv) medicine in cardiac imaging analysis. Here is the latest research.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

Social Learning

Social learning involves learning new behaviors through observation, imitation and modeling. Follow this feed to stay up to date on the latest research.

Cell Atlas of the Human Eye

Constructing a cell atlas of the human eye will require transcriptomic and histologic analysis over the lifespan. This understanding will aid in the study of development and disease. Find the latest research pertaining to the Cell Atlas of the Human Eye here.

Single Cell Chromatin Profiling

Techniques like ATAC-seq and CUT&Tag have the potential to allow single cell profiling of chromatin accessibility, histones, and TFs. This will provide novel insight into cellular heterogeneity and cell states. Discover the latest research on single cell chromatin profiling here.

Genetic Screens in iPSC-derived Brain Cells

Genetic screening is a critical tool that can be employed to define and understand gene function and interaction. This feed focuses on genetic screens conducted using induced pluripotent stem cell (iPSC)-derived brain cells.