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An Ugi reaction in the total synthesis of (-)-dysibetaine.

Angewandte Chemie (International ed. in English) (2009-01-29)
Jerry Isaacson, Yoshihisa Kobayashi
ABSTRACT

(-)-Dysibetaine has been synthesized in 11 steps from readily available L-malic acid (see scheme). The key step is a unique Ugi 4-center-3-component cyclization reaction, where an ester group acts as the carboxylic acid component. The use of 1,1,1,3,3,3-hexamethyldisilazane as an ammonia equivalent and a specially designed isocyanide leads to an expeditious synthesis.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Lithium bis(trimethylsilyl)amide, 97%
Sigma-Aldrich
Tris[N,N-bis(trimethylsilyl)amide]yttrium
Sigma-Aldrich
Tris[N,N-bis(trimethylsilyl)amide]samarium(III), 98%
Sigma-Aldrich
Potassium bis(trimethylsilyl)amide solution, 1 M in THF
Sigma-Aldrich
Potassium bis(trimethylsilyl)amide solution, 1.0 M in 2-methyltetrahydrofuran
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 1.5 M in THF
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 1.0 M in THF
Sigma-Aldrich
Sodium bis(trimethylsilyl)amide solution, 40% in THF
Supelco
Hexamethyldisilazane, for GC derivatization, LiChropur, ≥99.0% (GC)
Sigma-Aldrich
Hexamethyldisilazane, produced by Wacker Chemie AG, Burghausen, Germany, ≥97.0% (GC)
Sigma-Aldrich
Potassium bis(trimethylsilyl)amide, 95%
Sigma-Aldrich
Hexamethyldisilazane, reagent grade, ≥99%
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 1.0 M in hexanes
Sigma-Aldrich
Potassium bis(trimethylsilyl)amide solution, 0.5 M in toluene
Sigma-Aldrich
Sodium bis(trimethylsilyl)amide solution, 0.6 M in toluene
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 1 M in tert-butyl methyl ether
Sigma-Aldrich
Sodium bis(trimethylsilyl)amide, 95%
Sigma-Aldrich
Sodium bis(trimethylsilyl)amide solution, 1.0 M in THF
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 0.5 M in 2-methyltetrahydrofuran
Sigma-Aldrich
Lithium bis(trimethylsilyl)amide solution, 1 M in toluene
Sigma-Aldrich
Hexamethyldisilazane, ReagentPlus®, 99.9%