Volume 2015, Issue 31 p. 6900-6908
Full Paper

Synthesis of Alkynyl-Glycinols by Lewis Acid Catalyzed Propargylic Substitution of Bis-Imidates

Jekaterina Sirotkina

Jekaterina Sirotkina

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga 1006, Latvia, http://osmg.osi.lv/

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Liene Grigorjeva

Liene Grigorjeva

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga 1006, Latvia, http://osmg.osi.lv/

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Aigars Jirgensons

Corresponding Author

Aigars Jirgensons

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga 1006, Latvia, http://osmg.osi.lv/

Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga 1006, LatviaSearch for more papers by this author
First published: 30 September 2015
Citations: 9

Graphical Abstract

Racemic and enantioenriched alkynyl-glycinol derivatives can be synthesized by Lewis acid catalyzed cyclization reaction of bis-trichloroacetimidates into oxazolines.

Abstract

Racemic and enantioenriched alkynyl-glycinols can be synthesized by Lewis acid catalyzed cyclization reaction of bis-trichloracetimidates derived from alkynyl-glycols. The cyclization proceeds selectively to give 4-alkynyl-oxazolines as the propargylic substitution products. Enantioenriched bis-imidates that contain an alkyl or trimethylsilyl substituent at the acetylene gave oxazolines with complete inversion of configuration. In turn, considerable racemization was observed in the cyclization of bis-imidates that contain a phenyl substituent. The racemization for these substrates can be suppressed by introduction of the electronegative substituent at the phenyl ring. Oxazolines prepared by bis-imidate cyclization reaction can be readily transformed to protected alkynyl-glycol derivatives.