Disulfides as Sulfonylating Precursors for the Synthesis of Sulfone‐Containing Oxindoles

Abstract

Thef irst facile one-pot synthesis of sulfone-containing oxindoles with easily accessible disulfides as the sulfonylating precursors is described. This reactiono ccurs smoothly under transition metal-free conditions ands hows excellent functional group tolerance,a llowing the facile ande fficient green synthesis of various sulfone-containing oxindoles in aqueous solution. Preliminary mechanistic studies reveal that both water (H 2 O) and potassium persulfate (K 2 S 2 O 8 )c an be the oxygens ource of the sulfone groups in the products. Scheme 3. Scope of disulfides. Reaction conditions: 1a (0.2 mmol), 2 (0.3 mmol), K 2 S 2 O 8 (3.0 equiv.), and CH 3 CN/H 2 O( 1:1, 2mL) at 80 8 8Cunder an N 2 atmosphere for 24 h; Isolated yields based on 1a.Scheme4.Gram-scale reaction.

Visible‐Light‐Induced 3‐Component Synthesis of Sulfonylated Oxindoles by Fixation of Sulfur Dioxide

“…Purification by column chromatography ( n ‐hexane/EtOAc, 20:1→1:1) afforded 6b as an off‐white solid (109 mg, 93 %). Analytical data are consistent with the literature . R f = 0.20 ( n ‐hexane/EtOAc, 7:3); m.p.…”

“…No (long-lived) charge-transfer complexes could be observed. [43] Based on these results and findings from previous studies, [17,[20][21][22][23][24][25][26][27][28][29][30][31] the following reaction pathway is proposed (Scheme 6). DABSO and the iodonium salt form a charge transfer complex A.…”

“…Entry [a] Light source Solvent X Yield [%] [b] component, since N-arylacrylamides 2 are known as efficient traps for sulfonyl radicals. [17,[24][25][26][27][28][29][30][31] To our delight, irradiation of all three components in acetonitrile with blue LEDs (445 nm, 10 W) afforded the desired sulfonylated oxindole product 3a in 68 % yield after 8 hours at room temperature (Table 1, entry 1). No product formation was observed in the absence of light, even at elevated temperature (entries 2 and 3).…”

Iodine‐Triggered Aerobic Oxysulfonylation of Styrenes

“…β‐Hydroxysulfones are prepared via chemical or bio‐reduction of β‐ketosulfones, nucleophilic ring opening of epoxides with sulfinates, or via hydroxylation of α,β‐unsaturated sulfones . These efficient and flexible transformations have significant limitations such as involvement of multistep synthetic procedures for the synthesis of the starting materials, the production of unwanted by‐products, harsh reaction conditions, among others . In this regard, the development of efficient, direct and environmentally benign synthetic methods is highly desirable .…”

Ag/Pyridine Co-Mediated Oxidative Arylthiocyanation of Activated Alkenes

“…Other electron withdrawing groups such as CF 3 , CN, Ac, and CO 2 Me on the para -position of aryl rings were also compatible, affording the corresponding products 2j – n in good to excellent yields (77–93%). In particular, the para -NO 2 substituted substrate which is usually inert in radical cyclizations [ 40 ], afforded the desired oxindole 2m still with high yields. An obvious negative electronic effect from 4-methoxy on the para -position of the aryl moiety led to only a trace amount of the desired product 2o as determined by LC-MS analysis.…”