Zinc mediated activation of terminal alkynes: stereoselective synthesis of alkynyl glycosides.
نویسندگان
چکیده
Zinc mediated alkynylation reaction was studied for the preparation of C-glycosides from unactivated alkynes. Different glycosyl donors such as glycals and anomeric acetates were tested towards an alkynyl zinc reagent obtained from alkynes using zinc dust and ethyl bromoacetate as an additive. The method provides simple, mild and stereoselective access to alkynyl glycosides both from aromatic and aliphatic acetylenes.
منابع مشابه
Copper mediated stereoselective synthesis of C-glycosides from unactivated alkynes.
A highly stereoselective rapid C-glycosylation reaction has been developed between glycal and unactivated alkynes in the presence of coppertriflate and ascorbic acid at low catalyst loading and at room temperature. A wide variety of glycals and aryl acetylenes participate in the reaction smoothly. TfOH generated during the reduction of Cu(OTf)2 by ascorbic acid may be the active catalyst for th...
متن کاملGold(I)-catalyzed ring expansion of cyclopropanols and cyclobutanols.
The rearrangement of 1-alkynyl cyclobutanols and cyclopropanols to alkylidene cycloalkanones catalyzed by cationic triarylphosphine gold(I) complexes is described. The reaction tolerates terminal alkynes as well as alkyl, aryl, and halo-substitution at the acetylenic position and stereoselectively provides a single olefin isomer. The gold(I)-catalyzed rearrangement is stereospecific with regard...
متن کاملIron(III) chloride as an efficient catalyst for stereoselective synthesis of glycosyl azides and a cocatalyst with Cu(0) for the subsequent click chemistry.
A highly efficient and mild method for azido glycosylation of glycosyl β-peracetates to 1,2-trans glycosyl azides was developed by using inexpensive FeCl(3) as the catalyst. In addition, we demonstrated, for the first time, that FeCl(3) in combination with copper powder can promote 1,3-dipolar cycloaddition (click chemistry) of azido glycosides with terminal alkynes. Good to excellent yields we...
متن کاملA general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes
A novel metal-free strategy for a rapid and α-selctive C-alkynylation of glycals was developed. The reaction utilizes TMSOTf as a promoter to generate in situ trimethylsilylacetylene for C-alkynylation. Thanks to this methodology, we can access C-glycosides in a single step from a variety of acetylenes , i.e., arylacetylenes and most importantly aliphatic alkynes.
متن کاملThe stereoselective synthesis of α-amino aldols starting from terminal alkynes.
A new procedure for the stereoselective synthesis of syn α-amino β-oxy ketones is reported. It consists of two steps; in the first step, α-amino silyl enol ethers having a (Z) geometry are prepared from 1-alkynes via 1-sulfonyl-1,2,3-triazoles. In the second step, the silyl enol ethers undergo the TiCl4-mediated Mukaiyama aldol reaction with aldehydes to produce α-amino β-oxy ketones with excel...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Organic & biomolecular chemistry
دوره 12 40 شماره
صفحات -
تاریخ انتشار 2014