- Eco-Friendly Microwave-Assisted Scaleable Synthesis of 2-Cyanobenzothiazoles via N-Arylimino-1,2,3-dithiazoles
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The cyclization procedure of N-aryl iminodithiazoles into 2-cyanobenzothiazoles was re-investigated with the aim to develop original and environmentally friendly procedures. In this article, the benefits associated with the microwave methodology are reported and the opportunity to use solvent-free procedures in order to scale up organic synthesis is studied. The result obtained show that the strong thermal effects due to graphite/microwaves interaction can be efficiently used for the synthesis of heterocyclic molecules for which traditional methods failed or are less attractive.
- Frere, Stephane,Thiery, Valerie,Besson, Thierry
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p. 3795 - 3804
(2007/10/03)
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- Synthesis of heteroarenecarbonitriles by electrophilic cyanation; Reaction of metalated heteroarenes with p-toluenesulfonyl cyanide
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Several heteroarenecarbonitriles (5) were synthesized in moderate yields from heteroarenes (3) through metalation, followed by electrophilic cyanation using p-toluenesulfonyl cyanide. Similarly, trimethylsilylheteroarenes (8) were converted to heteroarenecarbonitriles (5) in good yields by treatment with p-toluenesulfonyl cyanide.
- Nagasaki, Izuru,Suzuki, Yumiko,Iwamoto, Ken-Ichi,Higashino, Takeo,Miyashita, Akira
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p. 443 - 450
(2007/10/03)
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- Stereochemistry of the olefin formation from anti and syn heterocyclic β-hydroxy sulfones.
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Reaction of aldehydes R2-CHO with the new lithio derivatives of 2-benzothiazoles or pyridines R1-CH2-SO2-Het afforded the corresponding β-hydroxy sulfones which are stable in the pyridine series and generally unstable in the benzothiazole series except for anti derivatives 10a and 20c. t-Butyl-dimethyl silyl ethers of all the heterocyclic β-hydroxy sulfones have been obtained by oxidation of the corresponding anti and syn sulfides, which have been stereoselectively prepared from the epoxides 17, 19, 21 and 23.The lithium or tetrabutylammonium alkoxides of heterocyclic β-hydroxy sulfones undergo an intramolecular addition to the neighboring C=N group followed by an S to O benzothiazole (or pyridine) transfer, and simultaneous extrusion of sulfur dioxide, ejection of benzothiazol-2(3H)-one anion and formation of the corresponding olefins.From the data of twenty cases studied, it can be concluded that the final elimination is entirely antiperiplanar only for the alkoxides of β-hydroxy-BT- or Pyr-sulfones anti or syn bearing saturated aliphatic chains R1 and R2 and for anti derivatives with R1 = R2 = C6H5.Due to their equilibration however, the alkoxides of numerous derivatives of heterocyclic (3-methylbut-2-enyl) or (phenylmethyl) sulfones do not follow entirely the above antiperiplanar elimination. Keywords: heteroaromatic sulfones / intramolecular ipso reaction / organolithium derivatives / stereochemistry / eliminations / olefination
- Baudin, J. B.,Hareau, G.,Julia, S. A.,Ruel, O.
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p. 336 - 357
(2007/10/02)
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