Categories: Synthesis of S-Heterocyles >
Related: benzo-fused O-Heterocyles, benzo-fused N-Heterocycles

Synthesis of benzofused S-Heterocycles and similar compounds

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Recent Literature

A simple catalytic system, in which PdCl₂ is the sole metal catalyst and DMSO functions as an oxidant and solvent, enables a synthesis of dibenzothiophenes in high yields from 2-biphenylthiols. This transformation offers broad substrate scope and operational simplicity.
T. Zhang, G. Deng, H. Li, B. Liu, Q. Tan, B. Xu, Org. Lett., 2018, 20, 5439-5443.

An operationally simple and efficient AgOTf-promoted tandem olefin isomerization/intramolecular hydroamination of 1,1-disubstituted alkenyl amines provides diverse 2-alkyl-substituted 1,3-X,N-heterocycles in very good yields through chemo- and regioselective C(sp³)-N bond formation with high atom economy. The reaction offers high functional group tolerance and broad substrate scope.
Y. H. Kim, D. B. Kim, S. W. Youn, J. Org. Chem., 2022, 87, 11919-11924.

A carbonylative cyclization of 2-iodosulfonamides using a Pd(OAc)₂/Xantphos catalyst system and phenyl formate as a CO source provides various saccharin derivatives under milder reaction conditions.
S. P. Chavan, Adithyaraj. K., B. M. Bhanage, Synlett, 2017, 28, 2000-2003.

In the presence of both DMSO and a tertiary aliphatic amine (triethylamine or N-methylpiperidine), sulfur reacts directly with a wide range of 2′-nitrochalcones to provide thioaurones in high yields even at room temperature and in the absence of a transition metal catalyst.
T. B. Nguyen, P. Retailleau, Org. Lett., 2018, 20, 186-189.

A facile silver(I)-catalyzed reaction of benzothiazol-2(3H)-ones with NaNO₂, or using AgNO₂ directly, enables a single-step transformation to the corresponding benzo[1,2,3]thiadiazoles in good yields, with wide functional group compatibility. It can also be performed in a one-pot manner from readily available 2-halogen-substituted benzothiazoles.
J. Nociarová, A. Purkait, R. Gyepes, P. Hrobárik, Org. Lett., 2024, 26, 619-624.

The reaction of o-haloaniline derivatives and carbon disulfide in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene at 80-140˚C provides the corresponding 1,3-benzothiazole-2(3H)-thione derivatives in good yields.
Y. Fu, X. Hu, Y. Chen, Y. Yang, H. Hou, Y. Hu, Synthesis, 2012, 44, 1477-1480.

In the presence of CuCl, a three-component reaction of o-iodoanilines and K₂S with TosMIC proceeded smoothly to yield the corresponding benzothiazolethiones in very good yields. Notably, isocyanide served as a carbon source and K₂S functioned as a sulfur source.
P. Dang, W. Zeng, Y. Liang, Org. Lett., 2015, 17, 34-37.

A molecular iodine-catalyzed oxidative cyclization of 2-aminopyridine/amidine and isothiocyanate via N-S bond formation enables the synthesis of N-fused and 3,4-disubstituted 5-imino-1,2,4-thiadiazole derivatives at ambient temperature. This transition-metal-free protocol provides a facile and highly efficient regiospecific synthesis of various 1,2,4-thiadiazole derivatives with good to excellent yields using inexpensive I₂ as a catalyst.
N. Tumula, N. Jatangi, R. K. Palakodety, S. Balasubramanian, M. Nakka, J. Org. Chem., 2017, 82, 5310-5316.

A Brønsted acid-catalyzed oxidative C-H functionalization of alkynyl thioethers provides valuable isothiochroman-3-ones in good yields under mild reaction conditions. This metal-free reaction offers a broad substrate scope and wide functional group tolerance.
Y.-Q. Zhang, X.-Q. Zhu, Y.-B. Chen, T.-D. Tan, M.-Y. Yang, L.-W. Ye, Org. Lett., 2018, 20, 7721-7725.

A one-pot method for the Sonogashira coupling and cyclization of 2-bromobenzenesulfonamides and terminal alkynes allows access to various substituted benzosultams regioselectively in excellent yields.
S. Debnath, S. Mondal, J. Org. Chem., 2015, 80, 3940-3948.

A water-gas shift reaction (WGSR) employing sodium 2-nitrobenzenesulfinates and α-bromo ketones enables a facile domino approach to benzothiazine 1,1-dioxides. This strategy is cost-effective and environmentally beneficial. The optimized reaction conditions demonstrated remarkable chemical tolerance to a wide range of electrically and sterically varied substituents on both coupling partners.
Y. Sharma, G. P. Pawar, V. D. Chaudhari, J. Org. Chem., 2023, 88, 701-710.

Treatment of various 2-amino-arylalkyl alcohols with isothiocyanates afforded thiourea intermediates, which were reacted in situ with molecular iodine in the presence of triethylamine to give 2-amino-4H-1,3-benzoxazines. The reaction of the thiourea intermediates with T3P as mild cyclodehydrating reagent and triethylamine as the base provides 2-amino-4H-1,3-benzothiazines.
V. P. R. K. Putta, N. Vodnala, R. Gujjarappa, U. Tyagi, A. Garg, S. Gupta, P. P. Pujar, C. C. Malakar, J. Org. Chem., 2020, 85, 380-396.

A copper-catalyzed three-component tandem reaction enables a convenient and practical synthesis of 1,4-benzothiazines from terminal alkynes, 2-iodophenyl isothiocyanates, and aqueous ammonia.
J.-J. Chu, B.-L. Hu, Z.-Y. Liao, X.-G. Zhang, J. Org. Chem., 2016, 81, 8647-8652.

A base-catalyzed intramolecular defluorination/O-arylation of readily available α-fluoro-β-one-sulfones provides a series of 3-fluoro-1,4-oxathiine 4,4-dioxide derivatives in very good yields. This process is triggered by a catalytic amount of tetramethylguanidine (TMG) as base and molecular sieves as both an adsorbent to remove HF acid and an activator to assist C-F bond cleavage.
L. Kang, J. Zhang, H. Yang, J. Qian, G. Jiang, Synlett, 2021, 32, 785-789.

While an N-S bond coupling/oxidation cascade of N-(2-mercaptophenyl)-N'-substituted ureas provides benzothiadiazin-3-one 1-oxides; the transformation of 2-mercaptobenzamides only occurs via N-S bond coupling to access benzisothiazol-3-ones in good yields. The photochemical syntheses offer mild conditions, excellent chemoselectivity, and functional group compatibility.
H. Li, Z. Xiong, S. Sheng, J. Chen, J. Org. Chem., 2023, 88, 16949-16959.

Sequential coupling-imination-annulation reactions of ortho-bromoarylaldehydes and terminal alkynes with ammonium acetate in the presence of a palladium catalyst under microwave irradiation gives various substituted isoquinolines, furopyridines, and thienopyridines in good yields.
D. Yang, S. Burugupalli, D. Daniel, Y. Chen, J. Org. Chem., 2012, 77, 4466-4472.

A thiolate anion promotes a transition-metal free cleavage of two carbon-sulfur bonds in 2,2′-bis(methylthio)-1,1′-biaryl derivatives. The subsequent dibenzothiophene-forming cyclization step proceeds through a concerted nucleophilic aromatic substitution (CS_NAr) mechanism.
Y. Masuya, Y. Kawashima, T. Kodama, N. Chatani, M. Tobisu, Synlett, 2019, 30, 1995-1999.

A visible-light-promoted and transition-metal-free photoredox-catalysis strategy provides thioxanthone derivatives (TXs) via hydrogen atom transfer, C-C formation, and oxidative dehydrogenation with high regioselectivity and reactivity. Significantly, this method can be used to produce commercial photoinitiators and drugs at the gram level.
W. Liao, J. Hou, H. Tang, X. Guo, G. Sheng, M. Jin, Org. Lett., 2023, 25, 6352-6356.

An N- and S-arylation sequence of o-sulfanylanilines enables an efficient synthesis of various N-arylphenothiazines under transition-metal-free conditions.
T. Matsuzawa, T. Hosoya, S. Yoshida, Org. Lett., 2021, 23, 2347-2352.

An isothiourea-catalyzed enantioselective formal [4+3] cycloaddition of various α,β-unsaturated carboxylic acid derivatives with 2-aminothiophenols proceeds via a reversible sulfa-Michael addition to α,β-unsaturated acylammonium intermediates, followed by an enantioselective formation of a seven-membered ring. This method enables a facile and divergent synthesis of optically active 2- and 3-substituted 1,5-benzothiazepines.
Y. Fukata, K. Yao, R. Miyaiji, K. Asano, S. Matsubara, J. Org. Chem., 2017, 82, 12655-12668.