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A Convenient Synthetic Route towards 3,5‐Bis(hydroxymethyl)pyrrolizidines: Stereoselective Synthesis of Unnatural (–)‐Hyacinthacine B 2
Author(s) -
Malatinský Tomáš,
Otočková Barbora,
Dikošová Lívia,
Fischer Róbert
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201900529
Subject(s) - stereocenter , stereoselectivity , chemistry , intramolecular force , stereochemistry , hydroxymethyl , substituent , ring (chemistry) , cycloaddition , nitrone , amination , combinatorial chemistry , enantioselective synthesis , organic chemistry , catalysis
A convenient synthetic route towards structurally intriguing hyacinthacines bearing an additional hydroxymethyl substituent at the C‐5 position is described. The strategy relies on syn ‐stereoselective 1,3‐dipolar cycloaddition of D‐mannose‐derived nitrone, which provides the required stereochemistry at the A‐ring and at the bridgehead C‐7a carbon atom in target pyrrolizidines. Consecutive Horner‐Wadsworth‐Emmons olefination and intramolecular reductive amination cyclization are employed for the B‐ring construction with an emphasis on the stereochemistry of the newly formed stereocenter at C‐5. The simplicity of this method is exemplified by effective and highly stereocontrolled synthesis of the unnatural (–)‐enantiomer of hyacinthacine B 2 .