Biomedical subjects
Publications and source records attributed to Hiroshi Kiyohara.
[Structure: see text] In addition reactions of enecarbamates and enamides, extremely high turnover frequency of the catalyst was observed in comparison with that of silicon enolate addition reactions. This is presumably due to fast transfer of the proton that locates on the nucleophiles.
[reaction: see text] Novel Mannich-type reactions of 1,3-dicarbonyl compounds with enecarbamates have been developed. Stable and storable enecarbamates work as surrogates of aliphatic aldehyde-derived imines, which are known to be difficult to isolate and store.
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Breast conserving surgery (BCS) is now a standard surgical treatment for early breast cancer. The number of patients with tumors under 3 cm who underwent breast conserving surgery overtook the number of patients who underwent total mastectomy for the first time in Japan in 2003. We have been employing breast conserving surgery with primary reconstruction using a lateral tissue flap (LTF), and have performed breast conserving surgery for 266 patients from 1990 to 2002. The incidence of local relapse was 5.6%. Although we did not irradiate a low risk group of 101 patients, our method is not inferior to other reports in which all cases underwent irradiation. Primary reconstruction with LTF has three advantages. The first is that we can avoid poly-surgery for breast reconstruction. The second is that the volume of the graft is maintained longer than reconstruction with a musculo-cutaneous flap. The third is that patients can avoid allergic reactions or granulomas as seen with artificial prosthesies. In conclusion, breast conserving surgery with immediate volume replacement with a LTF is a reasonable surgical procedure and has the advantage of avoiding unnecessary surgical procedures for reconstruction and surgical invasion without delaying the diagnosis of local relapse. Moreover, an adequate assessment of risk can spare low risk groups irradiation.
We have developed highly enantioselelctive reactions of silicon enolates with N-acyl-alpha-iminophosphonates leading to optically active alpha-amino phophonates. A copper (II)-diamine complex was shown to be effective in this reaction, and high levels of yield and selectivity were achieved. It is noteworthy that this reaction opens a way to various biologically important, optically active alpha-amino phosphonate derivatives.
[reaction: see text] Catalytic, enantioselective Mannich-type reactions of alpha-imino esters bearing readily removable substituents on nitrogen are described. Several N-carbamate-protected alpha-imino esters, which are readily prepared from 2-bromoglycine esters using a polymer-supported amine, reacted with silicon enolates to afford the desired adducts in high yields with high enantioselectivity using a copper(II)-diamine complex. Easy deprotection of the product amine and transformation to free alpha-amino acid derivatives have also been demonstrated.