Pivaloyl-protected glucosyl iodide as a glucosyl donor for the preparation of β-C-glucosides
A method for the selective synthesis of β-C-glucosides using α-D-tetra-O-pivaloylglucosyl iodide as a glucosyl donor is reported. Its diastereoselectivity differs from that of the respective acetyl-protected glucosyl bromide, as it reported in the literature under similar reaction conditions. The concentration of the catalyst, the solvent and the type of additive used are crucial factors that determine the reaction selectivity. This method has been applied in a short synthesis of dapagliflozin. The stability of α-D-tetra-O-pivaloylglucosyl iodide in CDCl3 and THF at reflux was also studied. All side products in the coupling and decomposition reactions were isolated and characterized, and possible pathways for their formation are proposed.
Triantakonstanti, Virginia V.,Toskas, Alexandros,Iordanidis, Nicolaos S.,Andreou, Thanos,Koftis, Theoharis V.,Gallos, John K.
supporting information
(2020/07/13)
Cyanide-Free Synthesis of Glycosyl Carboxylic Acids and Application for the Synthesis of Scleropentaside A
We have developed a cyanide-free strategy for the synthesis of glycosyl carboxylic acids, which can provide 1,2-trans or 1,2-cis glycosyl carboxylic acids and is compatible with common protecting groups. The synthetic utility was demonstrated by the synth
Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C-Glycosylation Reactions at Room Temperature
Pairing a range of bis(aryl) zinc reagents ZnAr2 with the stronger Lewis acidic [(ZnArF2)] (ArF=C6F5), enables highly stereoselective cross-coupling between glycosyl bromides and ZnAr2 without the use of a transition metal. Reactions occur at room temperature with excellent levels of stereoselectivity, where ZnArF2 acts as a non-coupling partner although its presence is crucial for the execution of the C(sp2)–C(sp3) bond formation process. Mechanistic studies have uncovered a unique synergistic partnership between the two zinc reagents, which circumvents the need for transition-metal catalysis or forcing reaction conditions. Key to the success of the coupling is the avoidance of solvents that act as Lewis bases versus diarylzinc compounds (e.g. THF).
Hernán-Gómez, Alberto,Orr, Samantha A.,Uzelac, Marina,Kennedy, Alan R.,Barroso, Santiago,Jusseau, Xavier,Lemaire, Sébastien,Farina, Vittorio,Hevia, Eva
supporting information
p. 10630 - 10634
(2018/08/01)
Cine Substitution with Arylzinc Reagents: Scope and Mechanistic Studies
The unexpected ability of arylzinc reagents bearing electron-donating substituents to react in a Friedel-Crafts fashion (cine) with electrophiles like perpivaloylated glucoside bromide and benzhydryl bromides in competition with organometallic coupling (ipso) is shown. The stereoelectronic factors required to promote the cine reactivity versus the classical ipso, and the mechanism of this alternative pathway, have been investigated. The Wheland intermediate is deprotonated intramolecularly in a 1,2-shift but also in a longer-range shift, leaving in this case the C-Zn untouched. In the latter case, it is possible to take advantage of this result for further functionalization.
Barroso, Santiago,Lemaire, Sébastien,Farina, Vittorio,Steib, Andreas K.,Blanc, Romain,Knochel, Paul
p. 2804 - 2816
(2016/04/26)
PROCESS FOR THE PREPARATION OF COMPOUNDS USEFUL AS INHIBITORS OF SGLT2
The present invention is directed to a novel process for the preparation of compounds having inhibitory activity against sodium-dependent glucose transporter (SGLT) being present in the intestine or kidney.
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Page/Page column 36
(2011/04/25)
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