Shinji Tanimori

Synthesis of a New Proline‐Derived Organic Catalyst and Its Evaluation for Direct Aldol Reaction

Abstract Aldol condensation of isobutylaldehyde with acetone catalyzed by amides and amines (1–8) derived from L‐proline gave β‐hydroxy ketone 17 in 80%ee.

Synthesis of novel quinoxaline derivatives and its cytotoxic activities

Substituted dihydroquinozalin-2-ones (1-16) have been synthesized easily by the use of copper-catalyzed coupling method. The reactions of 2-haloanilines with a variety of alpha-amino acids in the presence of copper (I) iodide gave corresponding 3-substituted dihydroquinozalin-2-ones in up to 86% yield. Some new quinoxalin-2-ones (2, 4, 5, 13 and 16) have moderate cytotoxic activity toward HeLaS3 cell lines at 4.9-18.1microM.

Enzymatic Synthesis of Hydroxycinnamic Acid Glycerol Esters Using Type A Feruloyl Esterase from Aspergillus niger

We found that hydroxycinnamic acid (HA) glycerol esters such as 1-sinapoyl glycerol and 1-p-coumaroyl glycerol can be synthesized through a direct esterification reaction using a type A feruloyl esterase from Aspergillus niger. The water solubilities of HA glycerol esters were higher than those of the original chemicals. HA glycerol esters absorbed ultraviolet light and scavenged 1,1-diphenyl-2-picrylhydrazyl radicals.

An efficient chemical synthesis of nicotinamide riboside (NAR) and analogues

A simple and efficient synthesis of nicotinamide riboside (NAR) 1 and derivatives 4 and 5 via trimethylsilyl trifluoromethanesulfonate (TMSOTf)-mediated N-glycosilation followed by spontaneous deacetylation by treating with methanol is reported.

Kinetic analysis of the reaction catalyzed by chitinase A1 from Bacillus circulans WL-12 toward the novel substrates, partially N-deacetylated 4-methylumbelliferyl chitobiosides

The kinetic behavior of chitinase A1 from Bacillus circulans WL‐12 was investigated using the novel fluorogenic substrates, N‐deacetylated 4‐methylumbelliferyl chitobiosides [GlcN‐GlcNAc‐UMB (2), GlcNAc‐GlcN‐UMB (3), and (GlcN)2‐UMB (4)], and the results were compared with those obtained using 4‐methylumbelliferyl N,N′‐diacetylchitobiose [(GlcNAc)2‐UMB (1)] as the substrate. The chitinase did not release the UMB moiety from compound 4, but successfully released UMB from the other substrates. k cat/K m values determined from the releasing rate of the UMB moiety were: 145.3 for 1, 8.3 for 2, and 0.1 s−1 M−1 for 3. The lack of an N‐acetyl group at subsite (−1) reduced the activity to a level 0.1% of that obtained with compound 1, while the absence of the N‐acetyl group at subsite (−2) reduced the relative activity to 5.7%. These observations strongly support the theory that chitinase A1 catalysis occurs via a ‘substrate‐assisted’ mechanism. Using these novel fluorogenic substrates, we were able to quantitatively evaluate the recognition specificity of subsite (−2) toward the N‐acetyl group of the substrate sugar residue. The (−2) subsite of chitinase A1 was found to specifically recognize an N‐acetylated sugar residue, but this specificity was not as strict as that found in subsite (−1).

Novel palladium-catalyzed oxazolidone synthesis

Abstract Reaction of dimethyl ( Z )-2-butenylene dicarbonate 1a with primary amines in the presence of [Pd(η 3 -C 3 H 5 )Cl] 2 and 1,1′-bis(diphenylphosphino)ferrocene (dppf) produced vinyl-oxazolidone compounds 2 in up to 70% yield.

Studies Directed Toward the Synthesis of Macrolactins: Asymmetric Synthesis of C3-C9 and C17-C24 Subunits of Macrolactin A

Abstract C3-C9 and C17-C24 subunits (2 and 3) of marine macrolide macrolactin A (1) were synthesized starting from known diol 5 and methyl (R)-3-hydroxybutylate 9 as chiral starting materials by straightforward manner.

A new pathway to chiral tetracyclic indolidines via Pauson–Khand reaction

Abstract Reaction of enynes 1 and 3 with Co 2 (CO) 8 in the presence of DMSO, NMO or TMANO as promoters produced tricyclic indolidine derivatives 5 and 7 stereoselectively in moderate to excellent yield. The stereochemistry at the C-7 position of the indolidines 5 and 7 was confirmed by their conversion into the bridged azacycles 10 and 13 .

Enantioselective construction of alicyclic bicyclo[3.1.0]hexane framework by double stereodifferentiation and its application for the synthesis of both enantiomers of vitamin D3 CD ring synthons

Abstract Good diastereoselectivity (85:15) was observed in the intramolecular cyclopropanation of the chiral unsaturated α-diazo-β-keto ester 9f , which possesses ( R )-pantolactone as a chiral auxiliary. The reaction was catalyzed by a chiral bis-oxazoline copper ( l ) complex 17 . The absolute stereochemistry of each generated diastereomer ( 10f and 11f ) was elucidated. Both enantiomers of the vitamin D 3 CD ring synthons ((−)- 21 and (+)- 22 ) were synthesized from (−)- 12 and (+)- 13 , respectively.

Biological Evaluation of Dodecaborate-Containing l-Amino Acids for Boron Neutron Capture Therapy

To develop a boron carrier for practical purposes, new boron-containing amino acids with an undecahydro-closo-dodecaboranylthio ([(10)B(12)H(11)S](2-)-) unit in the side chain of the α-amino acid have already been designed and synthesized. In the present paper, cytotoxicity, the incorporation amounts into tumor cells, and the tumor cell killing effects of these compounds were elucidated to evaluate their usefulness as boron carriers. Furthermore, the microdistribution of the amino acids in tumor cells was established.