The synthesis of several α-substituted N-Boc-protected prolines has been achieved by cross metathesis (CM) of N-Bocallylproline 5 with terminal long chain alkenes and alkenes bearing hydroxy, silyloxy, ester, and O-acetylglucosamido groups. The CM occurred with good selectivity and short reaction time under microwave heating conditions, affording yields in the range of 40–92%. Addition of Ti(OiPr)4 as a Lewis acid allowed a slight increase of the yield in the case of alkenes with Lewis basic substituents. The CM was also successfully applied to allylproline protected with trichloroacetaldehyde 4, but the intermediate products were less practical for further deprotection and elaboration.
Straightforward Synthesis of α-Substituted Prolines by Cross-Metathesis / M. LUMINI; F. M. CORDERO; F. PISANESCHI; A. BRANDI. - In: EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. - ISSN 1434-193X. - STAMPA. - 2008:(2008), pp. 2817-2824. [10.1002/ejoc.200800044]
Straightforward Synthesis of α-Substituted Prolines by Cross-Metathesis.
LUMINI, MARCO;CORDERO, FRANCA MARIA;BRANDI, ALBERTO
2008
Abstract
The synthesis of several α-substituted N-Boc-protected prolines has been achieved by cross metathesis (CM) of N-Bocallylproline 5 with terminal long chain alkenes and alkenes bearing hydroxy, silyloxy, ester, and O-acetylglucosamido groups. The CM occurred with good selectivity and short reaction time under microwave heating conditions, affording yields in the range of 40–92%. Addition of Ti(OiPr)4 as a Lewis acid allowed a slight increase of the yield in the case of alkenes with Lewis basic substituents. The CM was also successfully applied to allylproline protected with trichloroacetaldehyde 4, but the intermediate products were less practical for further deprotection and elaboration.File | Dimensione | Formato | |
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