Nouvelles approches de synthèse du tert-butane sulfinamide

La création de centres carbonés de géométrie sp3 chiraux est fondamentale en chimie organique afin de synthétiser des molécules biologiquement actives. Parmi la multitude de méthodologies existantes, l'utilisation du tert-butyle sulfinamide en tant que copule chirale s'est avéré être une solution efficace, notamment pour la synthèse d'amines chirales comme celle d'acides aminés par exemple. En effet, la chiralité portée par l'atome de soufre permet de contrôler très efficacement la stéréochimie du nouveau centre quaternaire créé et le clivage de la copule chirale est facilement réalisé en milieu acide. Malgré la multitude d'exemples de synthèse asymétriques utilisant cette copule, peu de méthodes de synthèse du tert-butyle sulfinamide énantiopure au niveau industriel sont décrites. De plus, elles se révèlent être onéreuses et donnant généralement des produits secondaires indésirables. Dans le cadre d'une collaboration avec un partenaire industriel, nous nous sommes intéressé à l'optimisation de voies de synthèse du tert-butyle sulfinamide décrites dans la littérature. Ces méthodes donnant souvent lieu à des produits instables ou des réactions contraignantes du point de vue industriel, nous nous sommes penché sur la formation de dérivés soufrés stables portant un groupement tert-butyle. Nos recherches nous ont permis de mettre au point une voie de synthèse originale utilisant le phtalimide. Les produits synthétisés sont d'une grande stabilité, obtenus avec d'excellents rendements et facilement purifiables. Via ce procédé, nous avons pu réaliser la synthèse du tert-butyle sulfinamide sous sa forme racémique et énantiopure.Creation of chiral sp3 carbon centre is a fundamental issue in modern organic chemistry, especially to synthesize biologically active molecules. Among the different known methods, the use of tert-butyl sulfinamide as a chiral auxilliary had shown excellent results, in particular for the synthesis of chiral amines such as amino acids. Despite of the large description of examples using this auxilliary, few methods of synthesis of this compound are described. Moreover, these pathways use expensive starting materials and produce undesirable secondary compounds. We developed with our industrial partner a new pathway for the synthesis of tert-butyl sulfinamide. First we concentrate our efforts to optimize known methods from the literature. The intermediate chloro-sulfinyl compounds are generally unstable and the conditions of reaction are rather difficult to implement. So we developed in a second time a new methodology using phthalimide skeleton as a stabilizing group in tert-butyl sulfur compounds. The synthesized products are very stable, obtained with good yields, and easily purified. This methodology permits us to obtain the tert-butyl sulfinamide in this racemic and enantiopur forms

Ethyl 2-[N-(tert-butyl­sulfin­yl)carbamo­yl]benzoate

The title compound, C14H19NO4S, was obtained in quanti­tative yield by Lewis acid-catalysed alcoholysis of a phtalimide precursor. An intra­molecular C—H⋯O hydrogen bond occurs. In the crystal, centrosymmetric dimers are formed by pairs of N—H⋯O hydrogen bonds between the sulfinyl O atoms and the carbamoyl N—H group of a neighboring mol­ecule. C—H⋯O inter­actions feature in the crystal structure

Iridium-Catalysed C-H Borylation of 2-Pyridones; Bisfunctionalisation of CC4

The high regioselectivity associated with the iridium-catalysed borylation of pyridones has been exploited to provide a very direct and efficient entry to C(10) doubly substituted CC4 variants of cytisine. Two approaches have been evaluated based on (i) C-H activation of cytisine (or an N-substituted derivative) followed by N-alkylation (to enable dimer formation) and (ii) direct C-H activation and borylation of CC4 itself. Both approaches provide access to C(10)-functionalized CC4 derivatives, but direct borylation of CC4 allows for a wider range of functional group interconversions to be tolerated.</p

Palladium-catalyzed direct C-H functionalization of benzoquinone

A direct Pd-catalyzed C=H functionalization of benzoquinone (BQ) can be controlled to give either mono- or disubstituted BQ, including the installation of two different groups in a one-pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents

Unlocking nicotinic selectivity via direct C‒H functionalization of (−)-cytisine

Differentiating nicotinic acetylcholine receptors (nAChR) to target the high-affinity nicotine α4β2 subtype is a major challenge in developing effective addiction therapies. Although cytisine 1 and varenicline 2 (current smoking-cessation agents) are partial agonists of α4β2, these drugs display full agonism at the α7 nAChR subtype. Site-specific modification of (−)-cytisine via Ir-catalyzed C‒H activation provides access to C(10) variants 6–10, 13, 14, 17, 20, and 22, and docking studies reveal that C(10) substitution targets the complementary region of the receptor binding site, mediating subtype differentiation. C(10)-modified cytisine ligands retain affinity for α4β2 nAChR and are partial agonists, show enhanced selectivity for α4β2 versus both α3β4 and α7 subtypes, and critically, display negligible activity at α7. Molecular dynamics simulations link the C(10) moiety to receptor subtype differentiation; key residues beyond the immediate binding site are identified, and molecular-level conformational behavior responsible for these crucial differences is characterized

Concise Entries to 4-Halo-2-pyridones and 3-Bromo-4-halo-2-pyridones

Methods for the synthesis of both simple 4-halo-2-pyridones and more functionalized 3,4-di-and (3,4,5-tri) halo-2-pyridones are described that are based on a combination of Sandmeyer and regioselective (Cu-mediated) halogenation, with a 2-chloro or a 2-benzyloxy moiety serving as a masked 2-pyridone