“Nonbiomimetic” Oxidations of Dihydropyridines

Introduction of Heteroatom-Based Substituents into 1,4-Dihydropyridines by Means of a Halogen-Mediated, Oxidative Protocol: Diamination, Sulfonylation, Sulfinylation, Bis-Sulfanylation, and Halo-Phosphonylation Processes

“…On the other hand, it would be highly desirable to profit from the nucleophilic character of the enamine moiety present in the molecule for synthetic purposes. [4] The introduction of nitrogen-, sulfur-, and phosphorousbased functionalities into the dihydropyridine ring system through the above-mentioned oxidative methodology would represent a highlight in this field, taking into account the potential impact of the resulting heterocyclic systems in natural product synthesis and in medicinal chemistry, where the preparation of diversely substituted (and functionalized) piperidines constitutes a highly pursued goal (Scheme 1). [2] More recently we have opened the door to the possibility of carrying out some ªnonbiomimeticº oxidations of 1,4-dihydropyridines in which the normal production of the corresponding pyridinium salt is avoided.…”

Dibenzothiophene Catabolism Proceeds via a Flavin-N5-oxide Intermediate

“…11,12 Since FMN-N5-oxide and organic peroxides are easily reduced by widely used biochemical reducing agents, (DTT, TCEP, NADH etc. ), 16 it is easy to miss this intermediate, and a systematic search for other FMN-N5-oxide-mediated reactions is merited.…”

“…No product was formed. The DszA reaction was also run in [ 18 O]-H 2 O/ 16 O 2 buffer to look for the oxygen incorporation expected for the hydrolysis of 11 to 4. No oxygen incorporation was detected (Figure 3A).…”

“…Decades ago flavin-N5-oxide 17 was considered as an intermediate in flavin-dependent oxygenase chemistry but was almost entirely replaced by the flavin hydroperoxide mechanistic paradigm. , Since FMN-N5-oxide and organic peroxides are easily reduced by widely used biochemical reducing agents, (DTT, TCEP, NADH etc. ), it is easy to miss this intermediate, and a systematic search for other FMN-N5-oxide-mediated reactions is merited.…”

Productive trapping of NAD-type radicals. Non-biomimetic reduction of pyridinium saltsElectronic supplementary information (ESI) available: experimental procedure and characterization data. See: http://www.rsc.org/suppdata/cc/b2/b201813f/

“…1 In recent years, we have developed what we call the nonbiomimetic oxidation of dihydropyridines. 2 In these reactions, the oxidation of the heterocyclic system takes place through bonding with electronegative atoms (by-passing the usual hydride transfer) and a wide variety of functionalized tetrahydropyridines are now available using this technique.…”