Synthesis of the Spermidine Alkaloids (−)-(2R,3R)- and (−)-(2R,3S)-3-Hydroxycelacinnine: Macrocyclization with Oxirane-Ring Opening and Inversion via Cyclic Sulfamidates
作者:Nikolai A. Khanjin、Manfred Hesse
DOI:10.1002/hlca.200390160
日期:2003.6
were achieved with trifluoroacetyl protection. Macrocyclization of the corresponding cis-oxiranes was unsuccessful for steric reasons. Inversion at OHC(3) via nucleophilic displacement of the cyclic sulfamidate derivative with NaNO2 led to (2R,3S)-macrocycles. The synthesized (−)-(2R,3S)-3-hydroxycelacinnine ((−)-1b) was identical to the natural alkaloid.
通过另一种途径合成了分别具有(2 R,3 R)和(2 R,3 S)绝对构型的大环内酰胺生物碱3-羟基celacinnine的两个差向异构体(-)- 1a和(-)- 1b涉及通过末端氨基在区域和立体选择性的环氧乙烷环上开环进行大环化(方案2和6)。提供适当的N保护的手性反式环氧乙烷前体(2 R,3 R一锅脱保护-大环化步骤在中等稀释度(0.005-0.01M)下进行。三氟乙酰基保护获得最佳收率(65-85%)。由于空间原因,相应的顺式-环氧乙烷的大环化是不成功的。在OHC(3)处通过环氨基磺酸盐衍生物与NaNO 2的亲核取代而发生反转,导致(2 R,3 S)-大环。合成的(-)-(2 R,3 S)-3-羟基celacinnine((-)- 1b)与天然生物碱相同。