Synthetic Study Using a New Active Reaction Species, Nitrosoketene

在此之前，我们报道了在非质子溶剂中将异硝基梅尔德拉姆酸与酮加热得到环硝基。这个反应涉及到由异硝基梅尔德拉姆酸衍生的亚硝基烯与酮的1,3-环加成反应。本课题通过亚硝基烯与多种手性酮反应合成手性环硝基酮，并通过硝基酮的不对称1,3-偶极环加成实现了修饰氨基酸的不对称合成。因此，亚硝基烯与(+)-诺蒎酮或(+)-苯醌反应得到一个单一的手性硝基酮异构体，而l-薄荷酮与亚硝基烯反应得到两个手性硝基酮异构体。其中一种异构体用于EPC合成改性氨基酸，如烯丙基甘氨酸和环戊基甘氨酸。此外，我们还与美国研究人员合作，首次成功地利用FT-IR光谱检测亚硝基烯。因此，我们发现异硝基甲基戊二酸在80ºC以上逐渐生成亚硝基戊二烯，然后在160ºC左右分解，在90ºC时亚硝基戊二烯的寿命为4 h。

Previously, we reported that heating of isonitroso Meldrum's acid with ketones in a aprotic solvent to give cyclic nitrones. This reaction involves the 1,3-cycloaddition of ketone with nitrosoketene derived from isonitroso Meldrum's acid. In this research project, we synthesized chiral cyclic nitrones from the reaction of nitrosoketene with various chiral ketones, and achieved the asymmetric synthesis of modified amino acids via asymmetric 1,3-dipolar cycloaddition of the nitrones. Thus, reaction of nitrosoketene with (+)-nopinone or (+)-camphenilone gave a chiral nitrone as a single isomer whereas l-menthone reacted with nitrosokene to give two isomers of chiral nitrones. One of these isomers was used for the EPC synthesis of modified amino acids such as allylglycine and cyclopentenylglycine. Furthermore, we first succeeded the detection of nitrosoketene using FT-IR spectroscopy under collaboration with American researchers. Thus, we found that nitrosoketene was gradually generated from isonitroso Meldrum's acid above 80ﾟC and then decomposed about 160ﾟC,and that life time of nitrosoketene was 4 h at 90ﾟC.