1218935-69-3Relevant academic research and scientific papers
Asymmetric total synthesis of vindoline
Kato, Daisuke,Sasaki, Yoshikazu,Boger, Dale L.
supporting information; experimental part, p. 3685 - 3687 (2010/05/15)
"Chemical equation presented" A concise asymmetric total synthesis of (-)-vindoline (1) is detailed based on a tandem intramolecular [4+2]/[3+2] cycloaddition cascade of a 1,3,4-oxadiazole inspired by the natural product structure, in which the tether linking the initiating dienophile and oxadiazole bears a chiral substituent that controls the facial selectivity of the initiating Diels-Alder reaction and sets absolute stereochemistry of the remaining six stereocenters in the cascade cycloadduct. This key reaction introduces three rings and four C-C bonds central to the pentacyclic ring system setting all six stereocenters and introducing essentially all the functionality found in the natural product in a single step. Implementation of the approach also required the development of a unique ring expansion reaction to provide a six-membered ring suitably functionalized for introduction of the .(6, 7)-double bond found in the core structure of vindoline and defined our use of a protected hydroxymetyl group as the substituent used to control the stereochemical course of the cycloaddition cascade.
Asymmetric total synthesis of vindorosine, vindoline, and key vinblastine analogues
Sasaki, Yoshikazu,Kato, Daisuke,Boger, Dale L.
supporting information; experimental part, p. 13533 - 13544 (2010/12/19)
Concise asymmetric total syntheses of vindoline (1) and vindorosine (2) are detailed based on a unique intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of 1,3,4-oxadiazoles inspired by the natural product structures. A chiral substituent on the tether linking the dienophile and oxadiazole was used to control the facial selectivity of the initiating Diels-Alder reaction and set the absolute stereochemistry of the remaining six stereocenters in the cascade cycloadduct. This key reaction introduced three rings and four C-C bonds central to the pentacyclic ring system setting all six stereocenters and introducing essentially all the functionality found in the natural products in a single step. Implementation of the approach for the synthesis of 1 and 2 required the development of a ring expansion reaction to provide a 6-membered ring suitably functionalized for introduction of the Δ6,7-double bond found in the core structure of the natural products. Two unique approaches were developed that defined our use of a protected hydroxymethyl group as the substituent that controls the stereochemical course of the cycloaddition cascade. In the course of these studies, several analogues of vindoline were prepared containing deep-seated structural changes presently accessible only by total synthesis. These analogues, bearing key modifications at C6-C8, were incorporated into vinblastine analogues and used to probe the unusual importance (100-fold) and define the potential role of the vinblastine Δ6,7-double bond.
