Transformations of unsaturated acyclic sugars into enantiomerically pure norbornene derivatives
作者:Derek Horton、Takayuki Usui
DOI:10.1016/0008-6215(92)84148-l
日期:1992.9
precursor dienophile 1 was also examined. Adducts 4a and 5a were transformed into such substituted carbocycles of known absolute configuration as the methyl esters (11 and 12) of norbornene (bicyclo[2.2.1]hept-2-ene)-6-carboxylic acid and nortricyclane (tricyclo[2.2.1.0(2,6)]heptane)-3-carboxy acid in optically pure form, specifically through decarbonylation reactions using RhCl(PPh3)3 (Wilkinson's complex)
衍生自L-阿拉伯糖的C7无环不饱和糖酯1及其对映异构体可作为方便的二烯亲油,用于手性转移,通过环加成反应合成光学纯的碳环衍生物。根据所用条件,可以控制1与环戊二烯的反应以制备5,6-二取代的降冰片烯加合物4a,5a和7a的制备途径。定量了来自该环加成反应的四种可能的异构体产物的分布,并且还研究了取代变化对前体亲二烯体1的影响。将加合物4a和5a转化为已知的绝对构型的取代碳环,如降冰片烯(双环[2.2.1]庚-2-烯)-6-羧酸和降三环烷(三环[2.2。]的甲酯(11和12)。 1.0(2,6)光学纯形式的庚烷)-3-羧酸,特别是通过使用RhCl(PPh3)3(Wilkinson络合物)和[Rh(dppp)2] Cl [dppp = Ph2P(CH2)3PPh2]进行脱羰反应进行。通过使用手性镧系转移试剂确定了12的光学纯度。