Sulfide and Sulfonyl Chloride as Sulfonylating Precursors for the Synthesis of Sulfone-Containing Isoquinolinonediones

Regioselective synthesis of isoquinolinonediones through remote unactivated C(sp3)-H bonds

Herein, a general strategy for the remote-site-selective cascade addition/cyclization of unactivated C(sp3)-H bonds in free alcohols and sulfonamides to build isoquinolinonedione skeletons is developed. The site selectivity occurs predominantly via a 1,5-hydrogen atom transfer (HAT) process, triggered by heteroatom-centred radicals generated directly under silver catalysis. A broad substrate scope and excellent regio-/chemo-selective control are demonstrated in this method.

Visible-Light-Driven Bifunctional Photocatalytic Radical-Cascade Selenocyanation/Cyclization of Acrylamides with KSeCN

A visible-light-induced radical-cascade selenocyanation/cyclization of N-alkyl-N-methacryloyl benzamides, 2-aryl-N-acryloyl indoles, and N-methacryloyl-2-phenylbenzimidazoles with potassium isoselenocyanate (KSeCN) was developed. The reactions were carried out with inexpensive KSeCN as a selenocyanation reagent, potassium persulfate as an oxidant, 2,4,6-triphenylpyrylium tetrafluoroborate as a bifunctional catalyst for phase-transfer catalysis, and photocatalysis. A library of selenocyanate-containing isoquinoline-1,3(2H,4H)-diones, indolo[2,1-a]isoquinoline-6(5H)-ones, and benzimidazo[2,1-a]isoquinolin-6(5H)-ones were achieved in moderate to excellent yields at room temperature under visible-light and ambient conditions. Importantly, the present protocol features mild reaction conditions, large-scale synthesis, simple manipulation, product derivatization, good functional group, and heterocycle tolerance.

A three-component reaction of cyclobutanone oxime esters, sulfur dioxide and N-alkyl-N-methacryloyl benzamides

A three-component reaction of cyclobutanone oxime esters, DABCO·(SO2)2 and N-alkyl-N-methacryloyl benzamides is described. This reaction proceeds without the addition of any oxidant or transition metal, affording sulfonyl-containing isoquinoline-1,3-(2H,4H)-diones in moderate to good yields. Various functional groups are tolerated well in this transformation. Mechanistic studies suggest that a radical pathway is involved, including β-scission, sulfur dioxide insertion, and intramolecular cyclization processes.

Silver-Catalyzed Cascade Radical Bicyclization Reaction: An Atom- and Step-Economical Strategy Accessing γ-Lactam Containing Isoquinolinediones

An efficient and convenient method for the cascade radical bicyclization of N-phenyl-4-pentenamides with N-methyl-N-methacryloylbenzamides under silver-catalyzed conditions is described. Based on this newly developed strategy, a variety of valuable γ-lactam containing isoquinolinediones can be effectively synthesized in one step within 0.5 h, during which two C-C bonds, one C-N bond, and two new N-heterocycles were formed concurrently. With N-aryl allyl carbamates, similar 2-oxazolidinone substituted isoquinolinedione compounds can likewise be produced. The approach demonstrates wide functional group compatibility, high step- and atom-economy, and the ability to be scaled up to gram quantities in a satisfactory yield. It marks the first instance of introducing γ-lactams into isoquinoline-1,3(2H,4H)-diones to construct linked hybrid drug-like molecules, thereby making this strategy highly attractive to drug discovery.

Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes

A mild, visible-light-induced, regioselective cascade sulfonylation-cyclization of 1,5-dienes with sulfonyl chlorides through the intermolecular radical addition/cyclization of alkenes C(sp²)-H was developed. This procedure proceeds well and affords a mild and efficient route to a range of monosulfonylated pyrrolin-2-ones at room temperatures.

Recent developments in the synthesis of the isoquinoline-1,3(2H,4H)-dione by radical cascade reaction

In recent years, isoquinoline-1,3(2H,4H)-dione compounds have attracted extensive attention from synthetic chemists, with the aim of finding simple, mild, green and efficient synthetic methods. In this review, we summarize the diverse range of synthetic methods employing acryloyl benzamides as key substrates to furnish isoquinoline-1,3-diones using different radical precursors, such as those containing carbon, sulphur, phosphorus, nitrogen, silicon and bromine. This will stimulate the interest of readers to engage in research in this field.

Recent progress in the radical α-C(sp3)-H functionalization of ketones

The direct use structurally simple ketones as α-ketone radical sources for α-C(sp³)-H functionalization is a sustainable and powerful approach for constructing complex and multifunctional chemical scaffolds with diverse applications. The reactions of α-ketone radicals with alkenes, alkynes, enynes, imides, and imidazo[1,2-a]pyridines have broadened the structural diversity and complexity of ketones. Through chosen illustrative examples, we outline the recent progress in the development of methods that enable the radical α-C(sp³)-H functionalization of ketones, with an emphasis on radical initiation systems and possible mechanisms of the transformations. The application of these strategies is illustrated by the synthesis of several biologically active molecules and drug molecules. Further subdivision is based on substrate type and reaction type.

Iron-catalyzed hydrogen atom transfer induced cyclization of 1,6-enynes for the synthesis of ketoximes: a combined experimental and computational study

An iron-catalyzed reductive radical cyclization/hydro-oximation of 1,6-enynes with tBuONO was developed, leading to functionalized benzofuran, benzothiophene, and cyclopentenyl-based ketoximes.

Sulfonyl radical-induced regioselective cyclization of 3-aza-1,5-enynes with sulfonyl chlorides to produce 1,2-dihydropyridines by copper catalysis

A Cu-catalyzed regioselective cyclization of 3-aza-1,5-enynes with sulfonyl chlorides for the synthesis of 1,2-dihydropyridines is described.

Palladium catalyzed asymmetric allylic alkylation of isoquinolinedione derivatives in the preparation of quaternary carbon stereocenters

A highly enantioselective allylic alkylation of isoquinolinedione derivatives under palladium catalysis was developed in the preparation of quaternary carbon stereocenters. Under standard reaction conditions, excellent yields and enantioselectivities were realized and the products could be transformed into dihydroisoquinolone with vicinal chiral carbon centers or THIQ core structures in short steps with high yields.

Cross coupling of sulfonyl radicals with silver-based carbenes: a simple approach to β-carbonyl arylsulfones

A radical–carbene coupling reaction of sulfonyl radicals and silver-based carbenes has been well established, which provides an efficient approach to various β-carbonyl arylsulfones.

Visible-light-promoted acyl radical cascade reaction for accessing acylated isoquinoline-1,3(2H,4H)-dione derivatives

A visible-light-promoted radical acylation/cyclization cascade reaction of N-methacryloylbenzamides with α-keto acids was developed to construct acylated isoquinoline-dione derivatives.

The continuous-flow electrosynthesis of 4-(sulfonylmethyl)isoquinoline-1,3(2H,4H)-diones from N-alkyl-N-methacryloyl benzamides under metal-free and oxidant-free conditions

An efficient and green electrochemical continuous flow approach has been developed for the synthesis of 4-(sulfonylmethyl)isoquinoline-1,3(2H,4H)-diones through sulfonylation of alkenes under metal-free and oxidant-free conditions.

Enantioselective amination of 4-alkylisoquinoline-1,3(2H,4H)-dione derivatives

A mild and efficient enantioselective amination of 4-alkylisoquinoline-1,3(2H,4H)-dione derivatives was established, which is compatible with a broad range of substrates and delivers the final products in excellent yields (up to 99%) and ee values (up to 99%) with low catalyst loading (down to 1 mol%). The synthetic potential of this methodology was also demonstrated in the gram scale level.

A mild and efficient enantioselective amination of 4-alkylisoquinoline-1,3(2H,4H)-dione derivatives was established and a broad range of amination products were prepared in excellent yields and ee values with low catalyst loading.

H· Transfer-Initiated Synthesis of γ-Lactams: Interpretation of Cycloisomerization and Hydrogenation Ratios

A cobaloxime/H2 system used to synthesize valuable γ-lactams from acrylamide molecules is described. In addition to cycloisomerized lactams, linear hydrogenated products were also observed. The amounts of the hydrogenation product were observed to correlate with the bulk of the substituent on the acrylamide nitrogen. Further analysis of the product distributions with experimental and computational studies suggested that while cyclization can occur from one C=C acrylamide rotamer, hydrogenation can occur from both. This observation was further evinced through calculation of the hydrogenation rate constant, which was observed to be ca. 102 faster than previously determined for a related system using n Bu3SnH.

Iodine-Catalyzed Odorless Synthesis of S-Thiocarbamates with Sulfonyl Chlorides as a Sulfur Source

A general and efficient protocol for the direct preparation of various S-thiocarbamates with readily available and inexpensive sulfonyl chlorides as an odorless sulfur source was developed. The employment of easily available reactants, excellent functional group tolerability, and mild reaction conditions make this process very practical.

Photocatalytic formation of carbon-sulfur bonds

This review summarizes recent developments in photocatalyzed carbon-sulfur bond formation. General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways.

Visible-light-induced sulfonylation/cyclization of vinyl azides: one-pot construction of 6-(sulfonylmethyl)phenanthridines

A facile and efficient protocol has been developed for sulfonylation/cyclization of vinyl azides under photoredox conditions.

CF3SO2X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF3SO2Cl

The recent progresses of the application of trifluoromethanesulfonyl chloride, CF₃SO₂Cl, in the formation of C–CF₃, C–SCF₃, C–SOCF₃, and C–Cl bonds are summarised in this second part of a two-part review published back-to-back on both sodium trifluoromethanesulfinate, CF₃SO₂Na, (Part 1) and trifluoromethanesulfonyl chloride, CF₃SO₂Cl (Part 2). There are many reactions in common between these two reagents but it should be noted that CF₃SO₂Cl reacts under reductive conditions while CF₃SO₂Na requires oxidative conditions. Electrophilic chlorination is obviously the exclusive preserve of CF₃SO₂Cl that has been exploited with emphasis in enantioselective chlorination.

Aerobic thiyl radical addition/cyclization of N-methacryloyl benzamides for the synthesis of isoquinoline-1,3(2H,4H)-dione derivatives

A highly effective dioxygen-triggered oxidative thiyl radical addition/cyclization of N-methacryloylbenzamides was explored. This method provides convenient access to a variety of useful sulfide-containing 4,4-disubstituted isoquinoline-1,3-diones.