کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5418028 | 1506972 | 2007 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Study of mechanisms of sulfonium keto ylides intramolecular cyclization
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Study of mechanisms of sulfonium keto ylides intramolecular cyclization Study of mechanisms of sulfonium keto ylides intramolecular cyclization](/preview/png/5418028.png)
چکیده انگلیسی
Mechanisms of monomolecular cyclization of N-maleyl protected keto stabilized sulfur ylides via three reaction pathways were investigated at the B3LYP/6-31G(d,p) level of theory. Structures and Gibbs free energies of intermediates and transition states of the reactions show that the Corey-Chaykovsky reaction occurs without trans-betaine formation and is least probable among those considered. Although methylthio pyrrolisinedione formation is thermodynamically most favorable, it has been found that an activation barrier of intramolecular 1,4-methyl shift, which is proposed to be a rate-limiting step in the reaction mentioned, is considerably high. However, the Wittig reaction, possessing lowest activation energy of the rate-limiting step, is thermodynamically disadvantageous. The presence of an alkyl substituent at the β-position of ylide and temperature influence only a new carbon-carbon bond formation at first stage of ylide cyclization.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure: THEOCHEM - Volume 807, Issues 1â3, 1 April 2007, Pages 55-60
Journal: Journal of Molecular Structure: THEOCHEM - Volume 807, Issues 1â3, 1 April 2007, Pages 55-60
نویسندگان
D.A. Chuvashov, I.V. Vakulin, R.F. Talipov, F.Z. Galin,