1307772-59-3Relevant articles and documents
A synthetic route to highly substituted 1,2,3,4-tetrahydroisoquinolines via Yb(OTf)3-catalyzed diastereoselective ring opening of bridged oxazolidines: Asymmetric synthesis of 2-azapodophyllotoxin
Srivastava, Ajay Kumar,Koh, Minseob,Park, Seung Bum
supporting information; experimental part, p. 4905 - 4913 (2011/06/10)
We herein report a robust and efficient synthetic route to highly functionalized enantiopure 1,2,3,4-tetrahydroisoquinolines (THIQs) from Garner aldehyde. We utilized the inherent chirality of Garner aldehyde through 1,2- and 1,3-/1,4-asymmetric inductions iteratively to obtain 1,2,3,4-tetrasubstitued THIQs using rigid and isolable bridged oxazolidines without any external chiral sources. All possible stereoisomers of bridged oxazoliodines were efficiently synthesized from L- and D-Garner aldehydes and transformed into fully functionalized THIQs via diastereoselective ring opening with various nucleophiles in the presence of Yb(OTf)3. This methodology furnished four out of eight possible diastereomers of 1,2,3,4-tetrasubstituted THIQs despite the electronic nature of substituents on the aryl rings. Finally, the enantioselective synthesis of 2-azapodophyllotoxin was achieved with an overall yield of 35.4 % (eight steps) from D-Garner aldehyde using this synthetic route. A concise and efficient synthetic route to highly functionalized enantiopure 1,2,3,4-tetrahydroisoquinolines (THIQs) from the Garner aldehyde via Yb(OTf)3-catalyzed diastereoselective ring opening of bridged oxazolidines is reported. This methodology was successfully applied to the synthesis of four stereoisomers of THIQ and the enantioselective total synthesis of 2-azapodophyllotoxin (1) in eight steps from D-Garner aldehyde in an overall yield of 35.4 %. Copyright
