A general approach to the asymmetric synthesis of vancomycin-related arylglycines by enolate azidation

✍ Scribed by David A. Evans; Deborah A. Evrad; Scott D. Rychnovsky; Thomas Früh; William G. Whittingham; Keith M. deVries

• Publisher: Elsevier Science
• Year: 1992
• Tongue: French
• Weight: 289 KB
• Volume: 33
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)91892-6

✦ Synopsis

The asymmetric synthesis of vancomycin-related 0t-azido arylglycines by direct azide transfer methodology is reported. Procedures for the conversion of the azides to N-protected arylglycines are provided.

Vancomycin, ristocetin, and related glycopeptide antibiotics 2 contain three to five racemization-prone arylglycines 3 within the heptapeptide aglycones. Accordingly, any attempt to synthesize any member of this family of natural products must incorporate methodology for the construction of these nonproteinogenic arylglycines. 4 In conjunction with our studies directed toward the synthesis of these antibiotics, we have prepared a number of functionalized arylglycines by the asymmetric azidation methodology (eq 1) developed in this laboratory. 4b,c A recent publication by Williams and co-workers 5 which also described the application of our methodology to the asymmetric synthesis of vancomycin-related arylglycines noted that, in certain instances, the N-sulfonyltriazene intermediate 2 could not be decomposed to the azido imide 3. The purpose of this Letter is to describe our investigations in this area, and to discuss successful procedures for the decomposition of the intermediate triazenes to the azide products.