5692-34-2Relevant articles and documents
Cobalt-catalysed C–H methylation for late-stage drug diversification
Ackermann, Lutz,Friis, Stig D.,Johansson, Magnus J.
, p. 511 - 519 (2020/06/05)
The magic methyl effect is well acknowledged in medicinal chemistry, but despite its significance, accessing such analogues via derivatization at a late stage remains a pivotal challenge. In an effort to mitigate this major limitation, we here present a strategy for the cobalt-catalysed late-stage C–H methylation of structurally complex drug molecules. Enabling broad applicability, the transformation relies on a boron-based methyl source and takes advantage of inherently present functional groups to guide the C–H activation. The relative reactivity observed for distinct classes of functionalities were determined and the sensitivity of the transformation towards a panel of common functional motifs was tested under various reaction conditions. Without the need for prefunctionalization or postdeprotection, a diverse array of marketed drug molecules and natural products could be methylated in a predictable manner. Subsequent physicochemical and biological testing confirmed the magnitude with which this seemingly minor structural change can affect important drug properties. [Figure not available: see fulltext.]
One-Pot Preparation of Aromatic Amides, 4-Arylthiazoles, and 4-Arylimidazoles from Arenes
Yamamoto, Takahiro,Togo, Hideo
, p. 4187 - 4196 (2018/08/21)
Simple treatment of arenes with α-bromoacetyl chloride and AlCl3, followed by the reaction with molecular iodine and aq. NH3, thioamides, or amidines gave the corresponding primary aromatic amides, 4-arylthiazoles, or 4-arylimidazoles in good yields, respectively. Aryl α-bromomethyl ketones are the key intermediates in those reactions. Primary aromatic amides were formed from arenes through the reaction of aryl α-bromomethyl ketones with molecular iodine and aq. NH3, and 4-arylthiazoles and 4-arylimidazoles were formed from arenes through the reactions of aryl α-bromomethyl ketones with thioamides and amidines, respectively, in one pot under transition-metal-free conditions.
Benzamide synthesis by direct electrophilic aromatic substitution with cyanoguanidine
Naredla, Rajasekhar Reddy,Klumpp, Douglas A.
experimental part, p. 4779 - 4781 (2012/09/07)
Cyanoguanidine is an inexpensive commodity chemical and it is found to be a useful reagent for the direct Friedel-Crafts carboxamidation of arenes. The reaction works best in an excess of Bronsted superacid, an observation suggesting the involvement of a superelectrophilic intermediate. Theoretical calculations indicate that the most stable diprotonated species involves protonation at the guanidine and cyano nitrogen atoms.
