Stereocontrolled Synthesis of Vicinal Diamines by Organocatalytic Asymmetric Mannich Reaction of <i>N</i>-Protected Aminoacetaldehydes: Formal Synthesis of (−)-Agelastatin A
The efficient and stereocontrolled synthesis of enantioenriched vicinal diamines is still a challenge to modern chemical methodology. We report here both syn- and anti-selective asymmetric direct Mannich reactions of N-protected aminoacetaldehydes with N-Boc-protected imines catalyzed by proline and the axially chiral amino sulfonamide (S)-3. This organocatalytic process represents the first example
1,2-二胺(邻二胺)基序存在于许多具有有趣生物活性的天然产物和许多手性分子催化剂中。对映体富集的邻二胺的高效立体控制合成仍然是现代化学方法的挑战。我们在这里报告了由脯氨酸和轴向手性氨基磺酰胺 (S)-3 催化的 N 保护氨基乙醛与 N-Boc 保护亚胺的顺式和反选择性不对称直接曼尼希反应。这种有机催化过程代表了曼尼希反应的第一个例子,使用 Z 或 Boc 保护的氨基乙醛作为 α-氮官能化醛亲核试剂在烯胺催化中的新入口。获得的旋光邻位二胺是有用的手性合成子,例如 (-)-agelastatin A 的正式合成。
syn-Selective Asymmetric Mannich Reaction of Sulfonyl Imines with Iminoesters Catalyzed by the N,N,N-Tridentate Bis(imidazolidine)pyridine (PyBidine)-Cu(OTf)2 Complex
Chiral ligand: The [PyBidine–Cu(OTf)2] (Tf=trifluoromethanesulfonate) complexcatalyzed the asymmetricMannichreaction of sulfonylimines and iminoesters to give the products in a high syn‐selective manner. For both 4‐toluene (Ts)‐ and 4‐nitrophenylsulfonyl (Ns)‐imines, the syn‐adducts were obtained in up to 99 % ee (see scheme).
Fine-Tuned Aminal Cleavage: A Concise Route to Differentially Protected Enantiopure <i>s</i><i>yn</i>-α,β-Diamino Esters
作者:Alma Viso、Roberto Fernández de la Pradilla、María L. López-Rodríguez、Ana García、Aida Flores、Marta Alonso
DOI:10.1021/jo035613j
日期:2004.3.1
A survey of routes for aminal cleavage of N-sulfinylimidazolidines has been carried out, and selective conditions to cleave the aminal moiety while preserving the sulfinamide group unaltered have been found. Thus, the treatment of enantiopure N-sulfinylimidazolidines with aqueous H3PO4 in THF affords enantiopure N-sulfinyldiamino esters in excellent yields, while the presence of MeOH as cosolvent allows for the simultaneous removal of the sulfinamide group and aminal cleavage. The behavior of these substrates in a variety of chemical transformations has been explored.