Highly diastereoselective approach to novel tetrahydrofuran-fused indolizidinols: a one-step formation of three contiguous stereocenters
摘要:
A concise and very efficient route to enantiopure tetrahydrofuran-fused indolizidinols, which could be considered as protected new indolizidindiols, is described in two-steps sequence starting from the known furoindolizidindiones. The key-step of these transformations was the formation, in one operation, of THF indolizidinols containing a lactam function by simultaneous highly diastereoseleclive catalytic hydrogenation of the carbonyl function and the furan ring. During these investigations, numerous catalysts in different combinations were tested and the impact of substrates on the reduction profile is discussed. (C) 2008 Elsevier Ltd. All rights reserved.
Highly diastereoselective approach to novel tetrahydrofuran-fused indolizidinols: a one-step formation of three contiguous stereocenters
摘要:
A concise and very efficient route to enantiopure tetrahydrofuran-fused indolizidinols, which could be considered as protected new indolizidindiols, is described in two-steps sequence starting from the known furoindolizidindiones. The key-step of these transformations was the formation, in one operation, of THF indolizidinols containing a lactam function by simultaneous highly diastereoseleclive catalytic hydrogenation of the carbonyl function and the furan ring. During these investigations, numerous catalysts in different combinations were tested and the impact of substrates on the reduction profile is discussed. (C) 2008 Elsevier Ltd. All rights reserved.
New homochiral 6-ethyl-7,8-indolizidinediol derivatives, related to the bioactive dihydroxylated indolizidine alkaloids, are reported to be easily accessible in four or five steps from enantiopure 9-hydroxy-octahydrofuro[3,2-f]indolizin-6(2H)-ones in good overall yields and high diastereomeric purities. The simple procedure used herein involves a regiospecific THF-ring opening as a key step, in addition to the C-Br linkage reduction, and the alcohol deprotection followed by lactam reduction. (C) 2010 Elsevier Ltd. All rights reserved.
Highly diastereoselective approach to novel tetrahydrofuran-fused indolizidinols: a one-step formation of three contiguous stereocenters
A concise and very efficient route to enantiopure tetrahydrofuran-fused indolizidinols, which could be considered as protected new indolizidindiols, is described in two-steps sequence starting from the known furoindolizidindiones. The key-step of these transformations was the formation, in one operation, of THF indolizidinols containing a lactam function by simultaneous highly diastereoseleclive catalytic hydrogenation of the carbonyl function and the furan ring. During these investigations, numerous catalysts in different combinations were tested and the impact of substrates on the reduction profile is discussed. (C) 2008 Elsevier Ltd. All rights reserved.