Synthetic Studies towards CH‐Diazomethane Sulfonamides: a Novel Type of Diazo Reagents

Abstract

Preparation of CH‐diazomethane sulfonamides has been developed for the first time. Their utility as a new type of diazo reagents was showcased in cycloaddition reactions with electron‐deficient alkynes and β‐nitro styrenes which delivered medicinally important pyrazole‐3‐sulfonamides in good to excellent yields.

From Rare Reagents to Rare Products: Regiospecific Silver‐Catalyzed [3+2] Cycloaddition of Aryl‐, Alkyl‐ and Aminosulfonyl Diazomethanes with Arenediazonium Tosylates

“…Sulfonyl diazomethanes 2a – h , along with three sulfamoyl diazomethanes 3a – c prepared as described recently, were employed in the cycloaddition reactions with a series of arenediazonium tosylates 6a – k (Figureà) which had earlier been found to be stable and easy to handle non‐hygroscopic solid reagents and, importantly, proven efficient partners in similar cycloaddition reactions with acyl diazomethanes …”

“…The latter represents a scarcely populated class of “terminal” diazo compounds which have been accessed predominantly by entirely different strategies . Another class of diazo compounds that had been completely absent from the synthetic chemistry toolbox are the recently reported CH‐diazomethanesulfonamides 3 . Both 2 and 3 appeared suitable partners for a [3+2] cycloaddition reaction with arenediazonium salts.…”

Metal-Free Synthesis of 1,5-Disubstituted 1,2,3-Triazoles

“…The two-step synthesis of triazoles 5a – k included the recently published metal-free, three-component synthesis of 1,2,3-triazoline-4-sulfonamides 1a – k using a single α-acetyl-α-diazomethane sulfonamide 2a reacting with the imines formed in situ from various aromatic aldehydes and aliphatic amines. Triazolines 1a – k were isolated chromatographically in good to excellent yields and subjected to thermal aromatization in ethanol.…”

CH-Diazomethane Sulfonamides Generated in Situ for Intramolecular [3+2] Cycloaddition of Alkynes: An Entry into Novel Pyrazole-Fused Five-Membered Sultams

“…Flash column chromatography was performed using silica gel Merk grade 60 (0.040−0.063 mm) 230−400 mesh (isocra c or gradient elu on as indicated). Starting a-diazo sulfonamides 15a-c were prepared as described previously 10.…”

“…11 The 'terminal' diazo sulfonamides 9 were employed in pyrazole synthesis 12 with acetylene monoand bis-carboxylic esters. 10 We reasoned that if one of the substituents (R 1 or R 2 ) in 9 was of propargylic nature (as in 12 prepared, foreseeably, by deacetylation of keto precursors 13), this might result in an intramolecular [3+2]-cycloaddition reaction leading to the hitherto unknown pyrazole-fused five-membered sultams 14 (Scheme 1). Herein, we report on the successful realization of this strategy.…”