Heterocyclic Natural Products Synthesis Using Reactive Meleimides that effect Asymmetric Cycloaddition with Unreactive Dienes

非对映选择性地合成了对映纯n -取代α -（2-外羟基-10-冰片酰基亚胺基）马来酰亚胺。得到的n -3-丁基-、N-TBDMS-和n -对甲氧基苄基马来酰亚胺与环戊二烯和呋喃发生Diels-Alder反应，得到相应的具有高度非对映选择性的环加合物。由n -丁基马来酰亚胺和环戊二烯衍生的Diels-Alder加合物经区域选择性还原和脱硫转化为-羟基内酰胺。得到的-羟基内酰胺通过非对映选择性N-酰基环化和逆diols - alder反应（闪蒸真空热解）进一步转化为(+)-吲哚吡啶和(+)-trachelanthamidine。用同样的方法，由N-TBDMS马来酰亚胺和环戊二烯衍生的diols - alder加合物转化为(+)- eleaeokanines A和c。diols - alder加合物与n -对甲氧基苄基马来酰亚胺和呋喃转化为手性-羟基内酰胺，该内酰胺进一步转化为有用的手性合成前体。通过非对映选择性n-酰基加成和二甲苯加热作用下的反向diols - alder反应，得到5-取代3-吡咯烷-2- 1和2,5-顺式二取代吡咯烷衍生物。

Enantiomerically pure N-substituted alpha-(2-exo-hydroxy-10-bornylsulfinyl)maleimides have been synthesized diastereoselectively. N-3-butynyl-, N-TBDMS- and N-p-methoxybenzyl maleimides obtained undergo Diels-Alder reactions with cyclopentadiene as well as furan to give the corresponding cycloadducts with a high degree of diastereoselectivity.The Diels-Alder adduct derived from the N-butynyl maleimide and cyclopentadiene was transformed into a gamma-hydroxy lactam via regioselective reduction followed by desulfinylation. The gamma-hydroxy lactam obtained has been further transformed into (+)-indolizidine and (+)-trachelanthamidine by diastereoselective N- acyliminocyclization and retro Diels-Alder reaction (flash vacuum pyrolysis) as key steps.By the similar methodology, the Diels-Alder adduct derived from the N-TBDMS maleimide and cyclopentadiene has been converted into (+)-elaeokanines A and C.The Diels-Alder adduct with the N-p-methoxybenzyl maleimide and furan was transformed into a chiral gamma-hydroxy lactam which has been further converted into a useful, chiral synthetic precursor, 5-substituted3- pyrrolin-2-one and 2,5-cis-disubstituted pyrrolidine derivative through diastereoselective N-acylimino addition and retro Diels-Alder reaction that was effected by heating in xylene.