- How Reaction Conditions May Influence the Regioselectivity in the Synthesis of 2,3-Dihydro-1,4-benzoxathiine Derivatives
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The exploration of different reaction conditions aiming to obtain both 2,3-dihydro-1,4-benzoxathiine-2-yl derivatives and 2,3-dihydro-1,4-benzoxathiine-3-yl ones is reported. The treatment of 1,2-mercaptophenol with an organic base and a specific 2-bromo acrylate results in a solvent- and substrate-dependent exclusive solvation of O- and S-anions, thus managing the regioselectivity.
- Casiraghi, Andrea,Valoti, Ermanno,Suigo, Lorenzo,Artasensi, Angelica,Sorvillo, Erica,Straniero, Valentina
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p. 13217 - 13227
(2018/10/24)
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- Preparation of α-haloacrylate derivatives via dimethyl sulfoxide-mediated selective dehydrohalogenation
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(Chemical Equation Presented) Dimethyl sulfoxide causes α/β-dihalopropanoate derivatives to undergo efficient, selective dehydrohalogenation to form α-haloacrylate analogues. A variety of α-halo Michael acceptors were prepared in dimethyl sulfoxide under mild, base-free conditions, including the preparation of α-bromoacrolein and α-chloro- and bromoacrylonitriles. Synthesis of these molecules has been reported in the literature to be difficult. Among all the existing dehydrohalogenation procedures, this protocol is the most facile, practical, and environmentally benign process.
- Li, Wei,Li, Jianchang,Wan, Zhao-Kui,Wu, Junjun,Massefski, Walter
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p. 4607 - 4610
(2008/03/13)
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- Novel syntheses of indolizines and pyrrolo[2,1-a]isoquinolines via benzotriazole methodology
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Indolizines and pyrrolo[2,1-a]isoquinolines are synthesized by 1,3- dipolar cycloadditions of pyridinium benzotriazolylmethylides or isoquinolinium benzotriazolylmethylides with ethylenes and acetylenes.
- Katritzky, Alan R.,Qiu, Guofang,Yang, Baozhen,He, Hai-Ying
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p. 7618 - 7621
(2007/10/03)
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- Synthesis, Molecular Structure, and Spectroscopical Properties of Alkenylphosphonic Derivatives. 1. Vinyl-, Propenyl-, (Bromoalkenyl)-, and (Cyanoalkenyl)phosphonic Compounds
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Several vinyl-, propenyl-, (bromoalkenyl)-, and (cyanoalkenyl)phosphonate derivatives have been synthesized.The (2-cyanovinyl)phosphonates have been obtained with an important improvement in the yield (40percent versus 6percent).The separation of the E and Z isomers of the cyano derivatives and their hydrolysis to the corresponding phosphonic acids have been studied.The bromination and dehydrobromination of some alkenylphosphonic derivatives have also been studied.Spectroscopical studies from UV, IR, Raman, and 1H, 13C, and 31P NMR have been performed in most of these derivatives.The C=C/P=O ? conjugation exists but it is weak in all these compounds.Dipole moments and C=C/P=O conformational populations have been calculated theoretically by ab initio methods.The effect of the solvent polarity on the conformational population has been observed by IR spectroscopy disclosing two C=C/P=O conformers.Experimental and theoretical results have been compared, a high level of agreement has been found.
- Sainz-Diaz, C. I.,Galvez-Ruano, E.,Hernandez-Laguna, A.,Bellanato, J.
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- Facile synthesis of α-anomeric pyrimidine nucleosides
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2-Amino-α-D-ribofurano[1',2':4,5]-2-oxazoline reacted with α- bromoacrylonitrile yielding 2,2'-anhydro-1-α-D-ribofuranosylcytosine which was converted to α-cytidine and α-2'-deoxycytidine. Reaction of 2-amino- α-D-ribofurano[1',2':4,5]-2-oxazoline and ethyl α-(bromomethyl)acrylate afforded 2,2'-anhydro-1-α-D-ribofuranosylthymine, a precursor of α- thymidine and α-ribothymidine.
- Sawai,Nakamura,Hayashi,Shinozuka
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p. 1647 - 1654
(2007/10/02)
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- SYNTHESIS OF 2,3,5,6-TETRAHYDROIMIDAZOTHIAZOLES
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The reactions of 2-amino-2-thiazoline with alkylating and acylating agents give initial reaction on the endocyclic nitrogen.Acyl groups, however, readily rearrange to the exocyclic nitrogen to give the products usually observed in these reactions.These observations clear up a considerable amount of confusion in the literature and lead to the efficient synthesis of 2,3,5,6-tetrahydroimidazothiazoles.
- Kaugars, Girts,Martin, Scott E.,Nelson, Stephen J.,Watt, William
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p. 2593 - 2604
(2007/10/02)
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- Method of dehydrating organic oxygenates
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Aqueous solutions of organic oxygenates, such as ethylene glycol may be dehydrated by
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