Asymmetric Synthesis of Five-membered Compounds by Transition Metal-Catalyzed Asymmetric Cyclizations of Enyne Systems

经过渡金属催化剂如钯、镍、钴、铑等处理后，炔类化合物发生环化反应。系统中加入手性助剂或手性配体为不对称合成环类化合物提供了一种新的策略。我们最近的结果与过渡金属沿着这些线不对称环化如下。在钯催化的反应中，使用含有两个具有相同取代基的烯烃部分和一个炔基的对称底物，通过在底物或手性配体中使用手性亚砜基或(S)-脯氨酸衍生的基团，提供了对映异构的反应产物。钯催化的不对称环异构化反应适用于含有手性亚砜基、(S)-脯氨酸或(S)-四氢异喹啉衍生基团作为手性助剂或使用手性配体的1,6-炔体系，为手性五元化合物提供了新的入口。在1,6-炔底物中加入更多的羧基提供了更高的非映体或对映体选择性，这可能是由于羧基与系统中钯催化剂的配位对所得到的中间钯配合物的构象进行了立体控制。利用手性膦配体首次催化制备了不对称Pauson-Khand反应，在该反应中，取代基具有显著的对映选择性。已经尝试引入手性有机硫官能团，如亚砜酰或亚砜酰胺基团。手性有机硫基团的效率稍低。通过使用(S)-蛋氨酸衍生底物进行Pauson-Khand反应，也揭示了有机硫官能团的参与。将(S)-蛋氨酸和(S)-S-甲基半胱氨酸衍生的手性底物与(S)-正缬氨酸和(S)-去亮氨酸衍生的无有机硫功能底物的结果进行比较，揭示了所涉及的亚砜基在战斗催化中的作用。通过x射线晶相分析确定了产物的结构。根据得到的立体化学结果，提出了反应机理。研究了钯催化（1,3-丁二烯基）环戊烯衍生物转化为环戊烯的立体化学反应。通过与作为起始底物的手性乙烯基亚砜的两种几何异构体的立体化学结果比较，揭示了手性亚砜基参与钯催化反应。少

Enyne compounds undergo cyclization reactions, upon treatment with transition metal catalysts such as palladium, nickel, cobalt, rhodium and so on. The use of chiral auxiliaries involved in the systems or chiral ligands provides a new strategy for asymmetric synthesis of cyclic compounds. Our recent results of asymmetric cyclizations with transition metals along these lines are as follows.1. The use of symmetric substrates involving two olefinic parts with the same substituents and an yne group in palladium-catalyzed reactions provided enantiotopic differentiating reaction products by using chiral sulfinyl or (S)-proline-derived groups involed in the substrates or chiral ligands.2. The palladium-catalyzed asymmetric cycloisomerizations were applicable to 1,6-enyne systems involving chiral sulfinyl, (S)-proline or (S)-tetrahydroisoquinoline-derived groups in the systems as chiral auxiliaries or using chiral ligands, providing a new entry to chiral five-membered compounds. Introduction o … More f a carboxyl group into the 1,6-enyne substrates provided higher diastereo- or enantioselectivity, presumably due to stereocontrol of the conformation of the resultant intermediary palladium complexes by coordination of the carboxyl groups to the palladium catalysts involved in the systems.3. The first catalytic asymmetric Pauson-Khand reaction has been developed by using chiral phosphine ligands, in which dramatic effects of the substituents were observed in achieving high enantioselectivity. Introduction of chiral organosulfur functionality such as sulfinyl or sulfinamide groups has been attempted. Slightly low efficiency was observed with the chiral organosulfur groups. Participation of organosulfur functionality was also revealed by the use of (S)-methionine-derived substrates for the Pauson-Khand reactions. The role of the sulfenyl groups involved in the chiral substrates derived from (S)-methionine and (S)-S-methylcystein in the cobatlt catalysis was reveiled in comparison with the results obtained from the substrates without organosulfur functionality, derived from (S)-norvaline and (S)-norleucine. The structure of the product was determined by the X-ray christallographic analysis. The reaction mechanism is proposed on the basis of the stereochemical results obtained.4. The stereochemistry of the palladium-catalyzed conversion of (1,3-butadienyl) cyclopentene derivatives into cyclopentenes was determined. The participation of the chiral sulfinyl groups in the palladium catalysis was revealed by the comparison with the stereochemical results between two geometrical isomers of the chiral vinylic sulfoxides employed as starting substrates. Less