| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
|
|---|
| Research Abstract |
We have elucidated that the function of ligands bearing tetraphenylphenyl group, which have rigid and spatially spread structure. The oxygen-, nitrogen-, and phosphorous-ligands having tetraphenylphenyl group were synthesized and were examined catalytic reactions using several kinds of metals. We aimed to find new reactions, high catalytic activity, and high selectivity compared to conventional catalysts. Indeed, in the last year we have explored the enhancement effect of stereoselectivity by the large asymmetric environment produced by tetraphenylphenyl group. The size of the tetraphenylphenyl group is approximately 1.3 nano meters. This is relatively larger than the ligands, which is used in usual homogeneous metal complex catalysts, however, smaller than supermolecular catalysts such as dendrimers. An advantage over the supermolecular catalysts is synthetic accessibility. In reality, we have examined asymmetric alcoholysis of vinyl ethers of 2,2'-dihydroxy-1.1'-biaryls and found tha
… More
t the diamine ligands bearing tetraphenylphenyl group exhibited higher performance : 1.3 times higher stereoselectivity and 2.0 times higher catalytic activity. This reaction is very useful because asymmetric synthesis of 2,2'-dihydroxy-1.1'-binaphtols is relatively easy but 2,2'-dihydroxy-1.1'-binphenols are not so easy. The reason is mainly due to the stability of radicals generating during the reaction. Therefore oxidative coupling of 2-naphtol is easy but phenol is difficult. We extended the research to the asymmetric synthesis of 2,2'-dihydroxy-1.1'-biaryls having phosphoryl and sulfonyl groups and succeeded kinetic resolution of these compounds in high selectivity. In addition, the compounds which have asymmetric center at phosphorous atom were examined to the reaction and found that kinetic resolution of these class of compounds can be carried out with high selectivities up to 39. Since asymmetric synthesis of these compounds are extremely difficult, the value of our reactions should be very high. Less
|
