Development of new function of N-oxide based on the electron-donating property of oxide oxygen

虽然有充分的文献证明，胺n-氧化物作为强大的电子对供体与各种受体分子形成配合物，但胺n-氧化物作为配体或催化剂的合成用途仍有待开发。我们发展了以下n -氧化物介导的有机反应。1.以丙炔氯为原料，原位制备丙基三氯硅烷和丙基三氯硅烷，通过手性n -氧化物催化，选择性地制备了具有光学活性的烯丙醇和同丙炔醇。2.在二异丙基乙胺存在下，以四氯硅烷为催化剂，利用手性联吡啶N，N'-氧化物作为催化剂，对中环氧化合物进行了对映选择性开环，得到了相应的氯丙烷，其对映选择性高达90%。3.采用手性N、N'-二氧化物和单齿N-氧化物作为催化剂，催化了三氯硅烯醚的对映选择性醛醇反应。N，N'二氧化物与无环烯醇醚的反应产生(E)-烯醇醚的反加合物和(Z)-烯醇醚的合加合物。环(E)-烯醇醚与N，N'二氧化物反应生成反加合物，而单齿N-氧化物主要生成合加合物。4.手性N，N'-二氧化镉-碘化镉配合物催化巯基对环烯酮和烯醛的共轭加成。使用1摩尔%的手性催化剂，硫化物的产率高，对映选择性好，达到78% ee。本反应是利用镉配合物作为对映选择性反应催化剂的第一个例子。5.以手性双喹啉N，N'-二氧化氮-三氟甲烷磺酸钪配合物为催化剂，实现了β-酮酯对α，β-不饱和羰基化合物的催化、对映选择性迈克尔加成反应。相应的Michael加合物产率高，对映选择性高达84% ee。

Although it is well documented that amine N-oxides act as powerful electron-pair donors to form complexes with a variety of acceptor molecules, synthetic utility of amine N-oxides as ligands or catalysts still remains to be developed. We have developed the following N-oxide-mediated organic reactions. 1.Optically active allenic and homopropargylic alcohols were selectively obtained by a chiral N-oxide-catalyzed reaction of aldehydes with propargyltrichlorosilane and allenyltrichlorosilane, prepared in situ from propargyl chloride. 2.An enantioselective ring opening of meso-epoxides with tetrachlorosilane in the presence of diisopropylethylamine exploiting chiral bipyridine N,N'-dioxides as catalysts affords the corresponding chlorohydrins in high enantioselectivities of up to 90% ee. 3.Chiral N,N'-dioxides and monodentate N-oxides were employed as catalysts in catalytic, enantioselective aldol reactions of trichlorosilyl enol ethers. The reactions of acyclic enol etheis using N,N'-dioxides resulted in the anti-adducts from (E)-enol ethers and the syn-adducts from (Z)-enol ethers. The reactions of cyclic (E)-enol ethers using N,N'-dioxides gave the anti-adducts, whereas monodentate N-oxides predominantly gave the syn-adducts. 4.Chiral N,N'-dioxide-cadmium iodide complex has been shown to catalyze enantioselective conjugate additions of thiols to cyclic enones and enals. The sulfides are generated in high yields and in good enantioselctivities up to 78% ee using 1 mol % of the chiral catalyst. The present reaction provides the first example of utilizing a cadmium complex as a catalyst in enantioselective reaction. 5.A catalytic, enantioselective Michael addition of β-keto esters to α,β-unsaturated carbonyl compounds was achieved by using a chiral biquinolme N,N'-dioxide-scandium trifluoromethanesulfonate complex as a catalyst. The corresponding Michael adducts were obtained in high yields and with enantioselectivities up to 84% ee.