Synthesis of N -Sulfonylformamidines by tert -butyl Hydroperoxide–Promoted, metal-free, direct oxidative dehydrogenation of aliphatic amines

Hexamethyldisilazane-Mediated Amidination of Sulfonamides and Amines with Formamides

Hexamethyldisilazane was reacted with formamides to generate N,N-disubstituent formimidamide, after which a reaction with sulfonamides was induced to form sulfonylformamidines. This protocol can be applied for arylformamidine formation in which anilines are used as substrates under optimized conditions. The advantages of this method are high efficiency, structural diversity in products with good yields, and applicability in large-scale operations.

Metal-Free Direct Access to N-Sulfonyl Amidines from Sulfonamides and Secondary Amines Involving Tandem C-N Bond Formations

We report a mild and efficient metal-free one-pot procedure for the synthesis of N-sulfonyl amidines via the direct reaction of sulfonamides with secondary amines without using any additives. A wide range of substrates with variety of functional groups is well tolerated under the reaction conditions. Preliminary mechanistic studies indicate that the secondary amine plays a dual role as a C1 source of the amidine group and an aminating agent. Synthetic utility of this method is shown in the late-stage functionalization of drug molecules on the gram scale.

Copper-Catalyzed C-N Bond Cleavage: Synthesis of N-Sulfonylformamidines from N-( 2-pyridinylmethyl)benzenesulfonamides

AIMS

Find an innovative approach to synthesizing N-sulfonylformamidines from new N source.

BACKGROUND

N-sulfonylamidines have gained considerable attention from school and industry because of unique bioactivity. Since Pinner's strategy, expanding the synthesis methods of N-sulfonylamidines has been the goal of many organic chemists over the past decades. Beside of the crash reaction conditions and the participation of undesirable reagents, the production of N-sulfonylamidines commonly required unstable ammonia and azides as the source of nitrogen which hindered the further development and application of N-sulfonylamidine derivatives.

OBJECTIVE

Find a stable N source to replace NaN3 or NH3 to synthesis N-sulfonylamidines.

METHOD

Firstly, N-( 2-pyridinylmethyl)benzenesulfonamides were smoothly synthesized via 2-pyridinemethanamine and sulfonyl chlorides. Then the reaction conditions of N-(2-pyridinylmethyl)benzenesulfonamides and N,N-dimethylformamide dimethyl acetal(DMF-DMA) were screened and optimized: the reaction was processed in glycol at 80 ℃ for 8 hours with the addition of 5 mol% Cu(OAc)2·H2O as catalyst.

RESULT

Taking the advantage of pyridin-2-ylmethyl, a scope of N-Sulfonylformamidines were synthesized from those N-(2-pyridinylmethyl)benzenesulfonamides under copper-catalyzed C-N bond cleavage.

CONCLUSION

This ready synthetic method will be more a promising inspiration of bioactive compound synthesis and drug development than of an innovative approach to synthesizing N-sulfonylformamidines.

Synthesis of amidines via iron-catalyzed dearomative amination of β-naphthols with oxadiazolones

An efficient and convenient method for the synthesis of amidines bearing a β-naphthalenone moiety catalyzed by cheap iron(ii) chloride is presented by employing oxadiazolones as the nitrene precursors.

Rapid and efficient synthesis of formamidines in a catalyst-free and solvent-free system

An operationally rapid and efficient synthesis of N-sulfonyl formamidines that proceeds under mild conditions was achieved by reaction of a mixture of an amine, a sulfonyl azide, and a terminal ynone under catalyst-free and solvent-free conditions. Terminal ynones provide the C source to formamidines via complete cleavage of C[triple bond, length as m-dash]C.

Visible-light enabled room-temperature dealkylative imidation of secondary and tertiary amines promoted by aerobic ruthenium catalysis

Employing sulfonyl azide as a nitrogen donor, a visible-light-enabled aerobic dealkylative imidation of tertiary and secondary amines involving C(sp³)–C(sp³) bond cleavage with moderate to excellent yields at room temperature is described. It has been demonstrated that this imidation could take place spontaneously upon visible-light irradiation, and could be facilitated considerably by a ruthenium photocatalyst and oxygen. An alternative mechanism to the previous aerobic photoredox pathway has also been proposed.

A photoredox dealkylative imidation of tertiary and secondary amines with sulfonyl azide facilitated by aerobic ruthenium-catalysis to afford sulfonyl amidine at room temperature is reported.

Catalyst-free one-pot, four-component approach for the synthesis of di- and tri-substituted N-sulfonyl formamidines

A straightforward one-pot, multicomponent approach was developed to synthesize di- and tri-substituted N-sulfonyl formamidines from sulfonyl chlorides, NaN3, ethyl propiolate, and primary/secondary amines under mild conditions without catalysts or additives. Structural analysis of the di-substituted sulfonyl formamidines indicated formation of the E-syn/anti isomeric form. Tri-substituted analogues only formed E-isomers.

Transition metal- and catalyst-free one-pot green method for the synthesis of N-sulfonyl amidines via direct reaction of sulfonyl azides with amines

In this report, a green synthesis of N-sulfonyl amidines via the direct reaction of tertiary or secondary amines with sulfonyl azides is described. Transition metal- and catalyst-free conditions were used for the synthesis of biologically important N-sulfonyl amidines. Further studies showed that the reaction proceeded via in situ aerobic oxidation of amines under reflux conditions.

Copper-Catalyzed Coupling of Sulfonamides with Alkylamines: Synthesis of (E)-N-Sulfonylformamidines

Herein, we describe an efficient copper-catalyzed coupling of sulfonamides with alkylamines to synthesize (E)-N-sulfonylformamidines. The reaction is accomplished under mild conditions without the use of a corrosive acid or base as an additive. It tolerates a broad scope of substrates and generates the products with exclusive (E)-stereoselectivity.

Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper-catalyzed three-component reaction of aryl acetylenes, amines, and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO₂ as the only byproduct. Transformation of the dioxazolones on the Cu catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu–C bond rather than undergoing an undesired Curtius rearrangement. For nonaromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 min. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple copper(I) iodide (CuI) as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol %. The herein reported procedure not only provides a new, practical, and direct route to N-acyl amidines but also represents a new type of C–N bond formation.