Solid phase aldol and conjugate addition reactions using Evans' oxazolidinone chiral auxiliary

Recent Advances in Asymmetric CC and C‐Heteroatom Bond Forming Reactions using Polymer‐Bound Catalysts

“…[123] Resin-bound Evans× auxiliaries have been reported by Shuttleworth et al for alkylation reactions in 1996, [124] Burgess et al in 1997 [125] and Davies et al [126] In 1998, Abell et al reported about a resin-bound Evans× oxazolidinone in aldol and conjugate addition reactions [127] synthesized on a solid support in three steps starting with tyrosine (122, Scheme 20). [115]…”

“…The derivatives of the chiral phosphine-phosphite ligand (R,S)-BINAPHOS 116a ± e by Nozaki et al [118] Scheme 20. Three-step synthesis of the resin-bound Evans× oxazolidinone 123 by Abell et al [127] Asymmetric CÀC and C-Heteroatom Bond Forming Reactions After propionalating the oxazolidinone part of the resin, the aldol reaction with benzaldehyde (124a) proceeds with a high degree of diastereoselectivity. The authors found only the syn diastereomer of 3-hydroxy-2-methyl-3-phenylpropionic acid (126) 21).…”

“…After eight times of Scheme 21. Resin-supported asymmetric aldol reaction by Abell et al [127] Scheme 22. Conjugated addition on a resin-supported Evans× auxiliary.…”

Stereoselektive Festphasensynthese von chiralen Piperidinderivaten an einem immobilisierten Galactoseauxiliar

“…Neben polymergebundenen chiralen Liganden und Katalysatoren [4] wurden vereinzelt trägergebundene chirale Auxiliare und deren Anwendung in Aldolkondensationen, [5] konjugierten Additionen, [6] 1,3-dipolaren Cycloadditionen [7] oder radikalischen Allylierungen [8] beschrieben. Wir berichteten bereits über die Synthese eines immobilisierten Galactosylamins als Auxiliar und dessen Anwendung in stereoselektiven Ugi-Reaktionen an der festen Phase.…”

Solid-phase asymmetric synthesis using a polymer-supported chiral Evans'-type oxazolidin-2-one

“…Polymer supports that have been used for immobilization include Wang [17][18][19][20][21][22] , Merrifield [18][19][20][21][23][24][25][26] , polystyrene [27][28][29] , TentaGel 18 , soluble polymer 30 and chloro-trityl resin 25 . These polymer-supported chiral oxazolidin-2-ones have been used in a range of asymmetric reactions including aldol reactions 17,23,24 , conjugate additions 23,29 , enolate alkylations 18,25 , Diels-Alder reactions 19 and 1,3-dipolar cycloadditions 20,21,26,30 . However, there are substantially fewer reports of reactions using polymersupported Evans oxazolidin-2-ones than might be expected when considering the popularity of this auxiliary for solution-phase synthesis 16 .…”