A simple, efficient Pd-catalyzed synthesis of N-sulfonylimines from organoboronic acids and tosylbenzimidoyl chlorides

Abstract

A simple and efficient synthesis of N-sulfonyl ketimines through a Pd-catalyzed cross-coupling reaction between organoboronic acids and tosylbenzimidoyl chlorides under mild conditions has been developed.

Stereospecific Suzuki, Sonogashira, and Negishi Coupling Reactions ofN-Alkoxyimidoyl Iodides and Bromides

“…Only two of these report coupling where the heteroatom attached to the nitrogen of the CN bond is sulfur or nitrogen. In 2008, Deng and Qian reported the palladium-catalyzed coupling of an N -tosyl imidoyl chloride with a boronic acid . In 2009, Grimm described the palladium-catalyzed coupling of cyclic hydrazonyl nonaflates with boronate esters and trifluoroborate salts .…”

Direct Synthesis of Enolizable N‐Sulfonyl Ketimines Under Microwave Irradiation

“…[12] Most yields lie in the moderate to good range, but it should be noted that these surpass the yields of all previous methods based on direct condensations. When compared to Ruano's [20] and other multistep syntheses, [26,27] this one-step synthesis provides similar yields, using an operationally far simpler procedure, reduced amounts of reagents, and remarkably shorter reaction times. To further prove the synthetic utility of the methodology we scaled up the synthesis to 6.5 mmol of acetophenone 1a.…”

“…Another multi-step procedure includes the palladium-catalyzed cross-coupling reaction between organoboronic acids and tosylbenzimidoyl chlorides. [27] A quick survey of the available methodologies for the synthesis of enolizable N-sulfonyl ketimines makes it apparent that this still remains challenging. [28] As part of our ongoing work on nucleophilic additions to N-sulfonyl ketimines, we required a reliable and quick procedure for their preparation.…”

Synthesis of N-Sulfonylimines Using CeCl3 Under Neutral Conditions

“…A number of methods for the synthesis of N-sulfonylimines have been reported. These have involved catalysis with Lewis acid, 10 titanium tetrachloride, 11 tellurium, 12 ruthenium, 13 Montmorillonite K-10, 14 oxidation with m-CPBA, 15 catalysis with zeolite, 16 DBU, 17 Pd, 18 Tf 2 O, 19 and rearrangements of sulfinate esters of oximes, 20 imine-transfer reaction, 21,22 and microwave facilitated acid catalysis. 23 However, these methods suffer from some limitations, such as a poor scope, unsatisfactory yields, expensive reagents and difficult scale-up.…”