S. Kajigaeshi

An effective chlorinating agent benzyltrimethylammonium tetrachloroiodate, benzylic chlorination of alkylaromatic compounds☆

Abstract The reaction of alkylaromatic compounds with benzyltrimethylammonium tetrachloroiodate in carbon tetrachloride in the presence of AIBN under reflux for several hours gave α-chloro-substituted compounds in fairly good yields.

Synthesis of Polymers by Using Fluorene. VI. Free-Radical and Anionic Polymerizations of 9-Fluorenyl and 9-Phenyl-9-fluorenyl Methacrylates

Abstract 9-Fluorenyl (FMA) and 9-phenyl-9-fluorenyl methacrylates (PFMA) were prepared from methacryloyl chloride with 9-fluorenol and from silver methacrylate with 9-phenyl-9-fluorenyl chloride, respectively. The polymerizations of FMA and PFMA were studied by using α,α′-azobisisobutyronitrile (AIBN), n-butyllithium (n-BuLi), and n-BuLi-(−)-sparteine (Sp) complex in toluene and tetrahydrofuran (THF). Only PFMA polymers obtained with the n-BuLi-Sp complex showed a specific rotation ([α]D 21 −3 to −16° in THF). The number-average molecular weights of the FMA and PFMA polymers were 7 700-16 900 and 1 400-4 700, respectively.

Bromination and oxidation with benzyltrimethylammonium tribromide

Abstract Our recent studies on effective bromination and oxidation using benzyltrimethylammonium tribromide (BTMA Br 3 ), stable solid, are described. Those involve electrophilic bromination of aromatic compounds such as phenols, aromatic amines, aromatic ethers, acetanilides, arenes, and thiophene, α-bromination of arenes and acetophenones, and also bromo-addition to alkenes by the use of BTMA Br 3 . Furthermore, oxidation of alcohols, ethers, 1,4-benzenediols, hindered phenols, primary amines, hydrazo compounds, sulfides, and thiols, haloform reaction of methylketones, N-bromination of amides, Hofmann degradation of amides, and preparation of acylureas and carbamates by the use of BTMA Br 3 are also presented.

An exploration of the binding site of aldolase using N-(ω-hydroxyalkyl)glycolamidobisphosphoric esters

N-(omega-Hydroxyalkyl)glycolamidobisphosphoric esters (P-O-CH2-CO-NH-(CH2)n -O-P), which are analogues of the aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13) substrate fructose 1,6-bisphosphate, were synthesized and used for probing its active site. These phosphate compounds competitively inhibited aldolase activity. The Ki value was lowest when the maximum distance between the phosphorus atoms of the bisphosphate was brought close to that of fructose 1,6-bisphosphate. The inhibitor constants, Ki, were compared to those of alkanediol monoglycolate bisphosphoric esters and alkanediol bisphosphate compounds, which were reported previously by Ogata et al. The values of Ki for the bisphosphate compounds containing an amide group, the amide bisphosphate compounds, were smaller than those for the bisphosphate compounds containing an ester group, the ester bisphosphate compounds, and those for alkanediol bisphosphates were the largest for the same distance between phosphorus atoms in these bisphosphates. The difference spectra of aldolase caused by binding of a saturating concentration of N-(omega-hydroxypropyl)glycolamidobisphosphoric ester resembled that of butanediol monoglycolate bisphosphoric ester. However, the effects of the amide bisphosphate compounds on the absorption spectrum of aldolase were smaller than those of the ester bisphosphate compounds for the same distance between phosphorus atoms in these bisphosphate compounds. These results suggest that the synthesized phosphate compounds bind to aldolase at the active site and the -CO-NH- group of the compounds might be held more tightly than the -CO-O- group by hydrogen bonds, presumably with the amino acid residues in the active site, such as Lys-146 or -229 and Asp-33 or Glu-187. On the other hand, the -CO-O- group might be more effective in changing the environment of the Trp-147 residue in the active site of this enzyme.

An exploration of the binding site of aldolase using alkyl glycolamido phosphoric esters and alkyl monoglycolate phosphoric esters

Alkyl glycolamido phosphoric esters (P-O-CH2-CO-NH-(CH2)n-CH3) and alkyl monoglycolate phosphoric esters (P-O-CH2-CO-O-(CH2)n-CH3), which are analogs of the aldolase substrate fructose-1-phosphate, were synthesized and use for probing the active site of rabbit muscle aldolase. The inhibition constants (Ki) were affected by the length of the alkyl groups of these compounds and a maximum value of Ki was observed between the number of methylene groups 2 and 4, depending on the type of compound. In the previous investigation, N-(omega-hydroxyalkyl)-glycolamido bisphosphoric esters (P-O-CH2-CO-NH-(CH2)n-O-P) and alkanediol monoglyclolate bisphosphoric esters (P-O-CH2-CO-O-(CH2)n-O-P) have a minimum Ki value between the number of methylene groups 1 and 4. The difference spectra of aldolase caused by binding of alkyl glycoamido phosphoric esters or alkyl monophosphates resembled that of their analogous bisphosphoric esters, but the intensity of absorbance was smaller than that of the bisphosphoric ester analogs. These results suggest that rabbit muscle aldolase has two binding sites for the phosphate groups on the entrance end of the active site cavity, the singly wound beta-barrel of the parallel alpha/beta class structure. The distance between the phosphate binding site Lys-107 in the beta-sheet structure (c) and Arg-148 in the beta-sheet structure (d) may possibly be expanded or contracted by the forms of the bending structure of the biphosphate compounds. Also, the change of distance between the beta-sheet structure (c) and (d) containing Trp-147, may have an effect on the environment of the tryptophan and cause a change of the absorbance of aldolase especially at 295-299 nm. On the other hand, the synthetic monophosphate compounds bind at only one of the two phosphate binding sites and have very little effect on the absorbance of Trp-147, in a similar manner as orthophosphate. The alkyl groups of monophosphate may be repelled by the ionic amino acid side chains, Asp-33, Lys-146, Glu-187 and/or Lys-229 in the middle of the active site cavity. However, the end of the long alkyl group of some monophosphates may possibly contact the hydrophobic bottom of the active site cavity without effect on the environment of Trp-147.