کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5161129 | 1501676 | 2017 | 5 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Assigning the stereochemistry of syn and anti β-trimethylsiloxy-α-trimethylsilyl alkanoic acid silyl esters using GIAO 1H NMR chemical shift calculations
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Assigning the stereochemistry of syn and anti β-trimethylsiloxy-α-trimethylsilyl alkanoic acid silyl esters using GIAO 1H NMR chemical shift calculations Assigning the stereochemistry of syn and anti β-trimethylsiloxy-α-trimethylsilyl alkanoic acid silyl esters using GIAO 1H NMR chemical shift calculations](/preview/png/5161129.png)
چکیده انگلیسی
The stereostructure of β-trimethylsiloxy-α-trimethylsilyl alkanoic acid silyl esters synthesized by Bellassoued et al. [J. Org. Chem. 2001, 66, 5054-5057] using Mukaiyama aldol reaction has been reassigned using density functional theory NMR 1H chemical shifts calculations. It is now concluded that the major diastereoisomer is syn and the minor is anti. Within this assignment, for all silyl esters, δHa(anti) > δHa(syn), δHb(anti) < δHb(syn), and 3JHa-Hb (anti) > 3JHa-Hb (syn). Since the experimental assignment was based on the stereostructure (E/Z) of the cinnamic acid obtained by elimination of trimethylsilyl 3-phenyl-3-(trimethylsiloxy)-2-(trimethylsilyl)propanoate in the presence of TiCl4 and on the assumption that this elimination is anti stereospecific in acidic medium, one arrives at the conclusion that the elimination of syn and anti β-trimethylsiloxy-α-trimethylsilyl alkanoic acid silyl esters is not anti stereospecific.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 1141, 5 August 2017, Pages 436-440
Journal: Journal of Molecular Structure - Volume 1141, 5 August 2017, Pages 436-440
نویسندگان
Slim Hadj Mohamed, Mahmoud Trabelsi, Benoît Champagne,