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

虽然它是有据可查的，胺N-氧化物作为强大的电子对供体，形成与各种受体分子的配合物，胺N-氧化物作为配体或催化剂的合成效用仍然有待开发。我们已经开发了以下N-氧化物介导的有机反应。1.通过手性N-氧化物催化的醛与炔丙基三氯硅烷和丙二烯基三氯硅烷的反应，选择性地获得光学活性的丙二烯醇和高炔丙醇。2.在二异丙基乙胺存在下，手性联吡啶N，N ′-二氧化物催化下，四氯硅烷对映选择性开环生成相应的氯代醇，其对映选择性高达90%ee. 3.手性N，N ′-二氧化物和单齿N-氧化物催化三氯硅烯醇醚的不对称Aldol反应.无环烯醇醚与N，N ′-二氧化物的反应生成（E）-烯醇醚的反加成物和（Z）-烯醇醚的顺加成物。环（E）-烯醇醚与N，N '-二氧化物反应生成反加合物，而单齿N-氧化物主要生成顺加合物。4.手性N，N '-二氧化物-碘化镉络合物已被证明催化硫醇对环烯酮和烯醛的对映选择性共轭加成。硫化物产生的高产率和良好的对映选择性高达78%ee使用1摩尔%的手性催化剂。本反应提供了在对映选择性反应中利用镉络合物作为催化剂的第一个实例。5.以手性联喹啉N，N ′-二氧化物-三氟甲磺酸钪配合物为催化剂，实现了β-酮酸酯对α，β-不饱和羰基化合物的催化Michael加成反应。以高产率得到相应的Michael加成物，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.