Dimethyl sulfoxide, DMSO
In the presence of dimethyl sulfoxide, the Burgess reagent efficiently and rapidly facilitates the oxidation of a broad range of primary and secondary alcohols to their corresponding aldehydes and ketones in excellent yields and under mild conditions. This oxidation can be combined with Wittig olefinations. A mechanism similar to those described for the Pfitzner-Moffatt and Swern oxidations is proposed.
P. R. Sultane, C. W. Bielawski, J. Org. Chem., 2017, 82, 1046-1052.
The use of DMSO in the presence of H2SO4 enables an efficient metal-free oxidation of benzylic alcohols to aromatic aldehydes in excellent yields. This oxidation proceeds in short reaction time without side products.
E. Sheikhi, M. Adib, M. A. Karajabad, S. J. A. Gohari, Synlett, 2018, 29, 974-978.
Oxidation of alkynes to α-dicarbonyl derivatives through a convenient one-pot procedure via a Brřnsted acid-promoted "hydration" and a DMSO-based oxidation sequence has been achieved in high yields.
Z. Wan, C. D. Jones, D. Mitchell, J. Y. Pu, T. Y. Zhang, J. Org. Chem., 2006, 71, 826-828.
Selective and quantitative conversion of thiols to disulfides was effected by dimethyl sulfoxide under mild conditions catalyzed by dichlorodioxomolybdenum(VI).
R. Sanz, R. Aguado, M. R. Pedrosa, F. Arnáiz, Synthesis, 2002, 856-858.
A metal-free and one-pot two-step synthesis of aryl carboxylic acids from aryl alkyl ketones has been performed with iodine as the catalyst, DMSO and TBHP as the oxidants. Various aryl alkyl ketones could be converted into their corresponding aryl carboxylic acids in very good yields.
L. Xu, S. Wang, B. Chen, M. Li, X. Hu, B. Hu, L. Jin, N. Sun, Z. Shen, Synlett, 2018, 29, 1505-1509.
An I2-promoted direct conversion of arylacetic acids into aryl carboxylic acids under metal-free conditions involves decarboxylation followed by an oxidation reaction enabled just by using DMSO as the solvent as well as an oxidant. Notably, aryl carboxylic acids are isolated by simple filtration technique and obtained in good to excellent yields, which makes this protocol applicable for large-scale synthesis.
H. P. Kalmode, K. S. Vadagaonkar, S. L. Shinde, A. C. Chaskar, J. Org. Chem., 2017, 82, 3781-3786.
Benzil derivatives such as diaryl 1,2-diketones are synthesized via a direct copper-catalyzed decarboxylative coupling reaction of aryl propiolic acids with aryl iodides followed by an oxidation. The reaction shows good functional group tolerance toward ester, aldehyde, cyano, and nitro groups. In addition, symmetrical diaryl 1,2-diketones are obtained from aryl iodides and propiolic acid in the presence of palladium and copper catalysts.
H. Min, T. Palani, K. Park, J. Hwang, S. Lee, J. Org. Chem., 2014, 79, 6279-6285.
An oxo-amination process with readily available N-bromosuccinimide (NBS) and secondary amines as N-sources and dimethyl sulfoxide (DMSO) as the oxidant provides amino alcohols in a single step. For the first time, the formation of reactive Me2S+-O-Br species generated by the interaction of NBS with DMSO has been proven.
P. K. Prasad, R. N. Reddi, A. Sudalai, Org. Lett., 2016, 18, 500-503.
Formation of unstable but reactive acyl nitroso intermediates from Nα-protected hydroxamic acids in the presence of iodine and DMSO enables an efficient and straightforward coupling with an amino component to yield dipeptide esters.
M. Krishnamurthy, T. M. Vishwanatha, N. R. Panguluri, V. Panduranga, V. V. Sureshbabu, Synlett, 2015, 26, 2565-2569.
A dimethyl sulfoxide (DMSO)-promoted oxidative amidation reaction between 2-oxoaldehydes and amines under metal-free conditions enables an efficient synthesis of α-ketoamides. Mechanistic studies supported an iminium ion intermediate that reacts with DMSO to provide the C1-oxygen atom of the product.
N. Mupparapu, S. Khan, S. Battula, M. Kushwaha, A. P. Gupta, Q. N. Ahmed, R. A. Vishwakarma, Org. Lett., 2014, 16, 1152-1155.
An iodine-catalyzed oxidative C-H/N-H cross-coupling enables an efficient construction of α-ketoimides in good to excellent yields from methyl ketones and benzamidines hydrochloride under metal-free and peroxide-free conditions.
X. Wu, Q. Gao, S. Liu, A. Wu, Org. Lett., 2014, 16, 2888-2891.
In an efficient α-hydroxylation of carbonyls compounds, readily available I2 or NBS was used as catalyst and DMSO as terminal oxidant. The reaction is mild, less toxic, easy to perform and allows the conversion of a diverse range of tertiary as well as secondary Csp3-H bonds.
Y.-F. Liang, K. Wu, S. Song, X. Li, X. Huang, N. Jiao, Org. Lett., 2015, 17, 876-879.
A smooth and efficient oxidation of isonitriles to isocyanates by DMSO as the oxidant is catalyzed by trifluoroacetic anhydride. The process is complete in a few minutes, forming dimethyl sulfide as the only byproduct. The newly formed isocyanates may be used directly or isolated in high purity by solvent evaporation.
H. V. Le, B. Ganem, Org. Lett., 2011, 13, 2584-2585.
Reactions of cinnamic acids with aromatic sulfinic acid sodium salts in the presence of a catalytic amount of manganese(II) acetate tetrahydrate in dimethyl sulfoxide provide vinyl sulfones in very good yields. The use of DMSO as solvent and the presence of air are critical in achieving good yields.
N. Xue, R. Guo, X. Tu, W. Luo, W. Deng, J. Xiang, Synlett, 2016, 27, 2695-2698.
A metal- and additive-free reaction of 1,2-dibenzyldisulfanes with amines using iodine as oxidant and DMSO as solvent at 100°C provides various thioamides in high yields.
S. Chen, Y. Li, J. Chen, X. Xu, L. Su, Z. Tang, C.-T. Au, R. Qiu, Synlett, 2016, 27, 2339-2344.
A direct difunctionalization protocol of alkenes with nitriles and thiols under metal-free synthesis conditions provides various β-acetamido sulfides with very good yields simply by using inexpensive molecular iodine as a catalyst, DMSO as a mild oxidant, and readily available thiols as thiolating reagents.
H. Cui, X. Liu, W. Wei, D. Yang, C. He, T. Zhang, H. Wang, J. Org. Chem., 2016, 81, 2252-2260.
In a I2-catalyzed direct conversion of cyclohexanones to substituted catechols under mild and simple conditions via multiple oxygenation and dehydrogenative aromatization processes, DMSO acts as the solvent, oxidant, and oxygen source. This metal-free and simple system provides highly valuable substituted catechols for drug discovery.
Y.-F. Liang, X. Li, X. Wang, M. Zou, C. Tang, Y. Liang, S. Song, N. Jiao, J. Am. Chem. Soc., 2016, 138, 12271-12277.
Dimethyl sulfoxide (DMSO) and N-iodosuccinimide mediate a metal-free regioselective 5-exo-dig oxidative cyclization of propargyl-substituted ynamides via in situ generated enol equivalents. The reaction allows easy access to functionalized pyrrolidone skeletons. The role of DMSO as oxidant in the transformation is clarified, and a tentative reaction pathway is proposed.
B. Prabagar, S. Nayak, R. Prasad, A. K. Sahoo, Org. Lett., 2016, 18, 3066-3069.
A One-Pot Tandem Approach for the Synthesis of 5-(Het)aryloxazoles from Substituted (Het)aryl Methyl Alcohols and Benzyl Bromides
K. S. V. Kumar, T. R. Swaroop, N. Rajeev, A. C. Vinayaka, G. S. Lingaraju, K. S. Rangappa, M. P. Sadashiva, Synlett, 2016, 27, 1363-1366.
A copper-catalyzed oxidative cyclization of aryl ketones with styrenes to furans, in which DMSO serves not only as a solvent but also as an oxidant, provides multiaryl-substituted furans from cheap and readily available starting materials.
Y. Wu, Z. Huang, Y. Luo, D. Liu, Y. Deng, H. Yi, J.-Fu. Lee, C.-W. Pao, J.-L. Chen, A. Lei, Org. Lett., 2017, 19, 2330-2333.
A one-pot tandem reaction of benzyl halides and o-aminobenzenethiol gives benzothiazoles in high chemical yields under mild conditions in DMSO in the absence of an additional oxidant. Both benzyl chlorides and bromides bearing a range of substituents proved to be suitable substrates.
C. Zhu, T. Akiyama, Synlett, 2010, 2345-2351.
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.
A regioselective 6-endo-trig intramolecular oxidative cyclization enabled an efficient synthesis of 2-aryl 4-substituted quinolines from stable and readily available o-cinnamylanilines with KOtBu as a mediator and DMSO as an oxidant at rt. The reaction showed a broad substrate scope with very good yields.
M. Rehan, G. Hazra, P. Ghorai, Org. Lett., 2015, 17, 1668-1671.
A practicable quinoline synthesis from aniline and two amino acids provides a wide range of quinolines with high efficiency and diversity including pharmaceutical derivatives, photochemical active compounds, and challenging scaffolds. Mechanistic studies revealed that I2 promotes decarboxylation, oxidative deamination, and selective formation of new C-N and C-C bonds.
J.-C. Xiang, Z.-X. Wang, Y. Cheng, S.-Q. Xia, M. Wang, B.-C. Tang, Y.-D. Wu, A.-X. Wu, J. Org. Chem., 2017, 82, 9210-9216.
A highly efficient I2-promoted formal [4 + 2] cycloaddition enables the synthesis of 2-acylquinolines from methyl ketones and arylamines using 1,4-dithane-2,5-diol as an ethylene surrogate. This reaction occurred via an iodination/Kornblum oxidation/Povarov/aromatization sequence with an important role of the arylamine substrate in promoting the reaction.
X. Wu, X. Geng, P. Zhao, J. Zhang, X. Gong, Y.-d. Wu, A.-x. Wu, Org. Lett., 2017, 19, 1550-1553.
A synergistic I2/amine promoted formal [4 + 2] cycloaddition of methyl ketones, arylamines, and aryl(alkyl)acetaldehydes provides various 2-acyl-3-aryl(alkyl)quinolines via an iodination/Kornblum oxidation/Povarov/aromatization sequence. Notably, the arylamine reactants also acted as indispensable catalysts to promote enamine formation.
X. Geng, X. Wu, P. Zhao, J. Zhang, Y.-D. Wu, A.-X. Wu, Org. Lett., 2017, 19, 4179-4182.
The reaction between isatoic anhydride, primary amines, and benzylic alcohols in the presence of HBr in DMSO at 80°C affords 2,3-dihydroquinazolin-4(1H)-ones in excellent yields via a metal-free oxidative C(sp3)-N coupling process.
N. R. E. Sheikhi, P. R. Ranjbar, Synlett, 2018, 29, 912-917.
DMSO as a mild and inexpensive oxidant enables an efficient and practical bromination and iodination of arenes with HX (X = Br, I) reagents. This oxidative system is amenable to late-stage bromination of natural products and kilogram-scale conversions.
S. Song, X. Sun, X. Li, Y. Yuan, N. Jiao, Org. Lett., 2015, 17, 2886-2889.
In an oxidative bromination of alkenes to 1,2-dibromo alkanes with HBr, dimethyl sulfoxide serves as the oxidant as well as cosolvent. Whereas simple olefins are brominated in very good yields, three of six styrene derivatives yielded bromohydrins under the reaction conditions.
M. Karki, J. Magolan, J. Org. Chem., 2015, 80, 3701-3707.
Highly regio- and stereoselective reactions of readily available 2-(methoxycarbonyl)-2,3-allenols with oxalyl chloride in the presence of Et3N or DMSO afforded methyl 2-(ethynyl)alk-2(E)-enoates and 2-(1′-chlorovinyl)alk-2(Z)-enoates, respectively, in good yields.
Y. Deng, X. Kin, C. Fu, S. Ma, Org. Lett., 2009, 11, 2169-2172.
"Activated" dimethyl sulfoxide efficiently dehydrogenates hydrazones to the respective diazo compounds at -78°C. Under optimized conditions, simple vacuum filtration provides solutions of pure diazo compounds from which stable diazo species can be isolated in high yield, or that can be directly used in subsequent reactions.
M. I. Javed, M. Brewer, Org. Lett., 2007, 9, 1789-1792.