Transition Metal-Free C–H Thiolation via Sulfonium Salts Using β-Sulfinylesters as the Sulfur Source

Abstract

We disclose a direct C(sp)−, C(sp 2 )−, and C(sp 3 )−H thiolation reaction using β-sulfinylesters as the versatile sulfur source.The key step of this protocol is chemoselective C−S bond cleavage of the sulfonium salts that are formed in situ from the corresponding alkenes, alkynes, and 1,3-dicarboxyl compounds with β-sulfinylesters. The successful capture of the acrylate byproduct supports a retro-Michael reaction mechanism.

Nonbasic Synthesis of Thioethers via Nickel-Catalyzed Reductive Thiolation Utilizing NBS-Like N-Thioimides as Electrophilic Sulfur Donors

“…1 H NMR (400 MHz, CDCl 3 ) δ 7.35 (2H, d, J = 7.8 Hz), 7.31 (2H, d, J = 8.4 Hz), 7.18 (2H, d, J = 7.8 Hz), 6.72 (2H, d, J = 2.4 Hz), 3.83 (3H, s), 2.38 (3H, s); 13 C­{ 1 H} NMR (101 MHz, CDCl 3 ) δ 159.3, 136.9, 132.0, 131.5, 130.1, 130.0, 129.6, 127.3, 121.2, 114.2, 55.4, 21.2. Spectra were consistent with literature data …”

Synthesis of Alkynyl Sulfides: Alkynyl Trifluoromethyl Sulfides and Thiocyanates

“…In 2021, Cheng developed Tf 2 O-accelerated thiolation of terminal alkynes by applying β-sulfinylesters as a sulfur source to prepare alkynyl sulfides. [45] In the presence of Tf acetylene and thioalkylation of alkyl-substituted β-sulfinylesters with phenylacetylene were successful, resulting in the corresponding products 12 k-12 r in 58-97 % yields (Scheme 4). It was worth mentioning that this thiolation, proceeded at rt in the absence of any metal catalysts.…”

“…Tf 2 O-Accelerated thiolation of alkynes with β-sulfinylesters. [45] Scheme 5. Tf 2 O-Promoted thiolation of alkynes with methyl sulfoxides.…”

“…In 2021, Cheng developed Tf 2 O‐accelerated thiolation of terminal alkynes by applying β‐ sulfinylesters as a sulfur source to prepare alkynyl sulfides [45] . In the presence of Tf 2 O, thiolation of terminal alkynes 11 with β‐ sulfinylesters 10 underwent smoothly to give the desired alkynyl sulfides 12 in moderate to high yields.…”

Synthesis of alkynyl sulfides via base-promoted nucleophilic ring-opening of α-bromostyrene sulfonium salt

“…The key step of this protocol is the chemoselective C–S bond cleavage of sulfonium salts that are formed in situ from the corresponding alkynes (Scheme 1d). 12 In our pursuit of developing a novel and efficient method for synthesizing alkynyl sulfides, we directed our attention towards cyclic sulfonium salts since they had shown promising results in the formation of organic sulfides. 13 Herein, we report a practical and efficient strategy for the formation of alkynyl sulfides using tetramethylene sulfoxide as the sulfur source via an α-bromostyrene sulfonium salt.…”