High diastereoselection in the alkylation of siloxy-substituted methyl cyclopropanecarboxylates: consequence of a pyramidal ester enolate anion?

1,2:5,6-Di-O-isopropylidene-α-D-gulofura

1,2:5,6-Di-O-isopropylidene-α-D-gulofuranose as a Chiral Auxiliary in the Diastereoselective C Methylation of Ester Enolates. The Influence of the Base on the Stereochemistry of Enolate Formation and Alkylation

✍ Mulzer, Johann ;Hiersemann, Martin ;Buschmann, Jürgen ;Luger, Peter 📂 Article 📅 2006 🏛 John Wiley and Sons 🌐 English ⚖ 551 KB

## Abstract The __C__ methylation of the carbohydrate‐derived __O__‐chiral esters 5a‐d to derivatives 8 proceeds with (__R__) selection of 1:1 to 10:1 and depends primarily on the base used for enolate generation. Lithium 2,2,6,6‐tetramethylpiperide (LTMP) shows the highest and lithium hexamethyldi