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Your search keyword '"Toshiaki Saitoh"' showing total 11 results
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11 results on '"Toshiaki Saitoh"'

3. An Efficient and Convenient Synthesis of 4,5,6,7-Tetrahydrothieno[3,2-c]pyridines by a Modified Pictet-Spengler Reaction via a Formyliminium Ion Intermediate

Author

Yoshie Horiguchi, Michikazu Kitabatake, Aki Hashimoto, Toshiaki Saitoh, Takehiro Sano, and Kunihiko Mohri

Subjects
Pharmacology, Pictet–Spengler reaction, Chemistry, Organic Chemistry, chemistry.chemical_element, Medicinal chemistry, Analytical Chemistry, Catalysis, Ion, Formylation, chemistry.chemical_compound, Trifluoroacetic acid, Ethylamine, Titanium
Abstract

A synthesis of N-formyl-4,5,6,7-tetrahydrothieno[3,2-c]pyridines (5) was achieved in a highly efficient manner via trifluoroacetic acid catalyzed cyclization of formyliminium ion (4), which was produced by imination of 2-(2-thienyl)ethylamine (1) and a carbonyl compound (2) using titanium(IV) tetraisopropoxide followed by formylation with acetic-formic anhydride in a one-pot procedure. This modified Pictet-Spengler reaction provides a convenient method for preparing 4,5,6,7-tetahydrothieno[3,2-c]pyridines (6) possessing various substituents at C-4.

Published
2010

4. Facile Synthesis of 1-Aryl-2,3-dihydro-1H-isoindoles by Cyclization of N-Formyliminium Ion via Geometrically Disfavored 5-Endo-trig Process

Author

Yoshie Horiguchi, Michikazu Kitabatake, Toshiaki Saitoh, and Takehiro Sano

Subjects
Pharmacology, chemistry.chemical_compound, Pictet–Spengler reaction, chemistry, Isoindoles, Aryl, Scientific method, Acid catalyzed, Organic Chemistry, Combinatorial chemistry, Analytical Chemistry, Ion
Abstract

Synthesis of 1-aryl-2,3-dihydro-1H-isoindoles (isoindolines) (10) was achieved in a highly effective manner via acid catalyzed cyclization of N-formyliminium ion (8) obtained from 2,3-dimethoxybenzylamine and carbonyl compounds with acetic-formic anhydride under a one pot procedure. This Pictet-Spengler type reaction provides a convenient method for preparing 1-arylisoindolines.

Published
2009

5. A Facile Synthesis of 1,1-Disubstituted 1,2,3,4-Tetrahydro-b-carbolines via Trifluoroacetic Acid Catalyzed Pictet- Spengler Reaction Using Titanium(IV) Isopropoxide as an Imination Reagent

Author

Toshiaki Saitoh, Akiko Kida, Takehiro Sano, Masayoshi Nakamura, Yoshie Horiguchi, and Hirokazu Kodama

Subjects
Pharmacology, Tryptamine, Pictet–Spengler reaction, General method, Organic Chemistry, chemistry.chemical_element, Analytical Chemistry, Catalysis, chemistry.chemical_compound, chemistry, Reagent, Trifluoroacetic acid, Organic chemistry, Titanium
Abstract

A synthesis of 1,1-disubstitued 1,2,3,4-tetrahydro-β-carbolines (13) was achieved in a highly effective manner via the trifluoroacetic acid catalyzed Pictet-Spengler reaction of the keto imines (9) prepared from tryptamine (8) with acyclic and cyclic ketones using titanium(IV) isopropoxide as the imination reagent under one pot procedure. This reaction provides a convenient and general method for preparing various 1,2,3,4-tetrahydro-β-carbolines derivatives.

Published
2003

6. Synthesis of 1,2-Dihydrobenz[c]azepin-3-one via Acid-catalyzed Cyclization of N-Arylmethyl-N-methyl-3-phenylsulfanylacrylamide

Author

Tomoko Kashiwagi, Toshiaki Saitoh, Jun Toda, Mayumi Itagaki, Yoshie Horiguchi, Takehiro Sano, and Lisa Katura

Subjects
Pharmacology, chemistry.chemical_compound, Chemistry, Acid catalyzed, Acrylamide, Organic Chemistry, Medicinal chemistry, Analytical Chemistry
Abstract

Treatment of N-arylmethyl-N-methyl-cis-3-phenylsulfanyl acrylamide (5) with p-toluenesulfonic acid induced two reactions; cyclization to 1,2-dihydrobenz[c]azepin-3-ones (7) and N-dearylmethylation to N-methylacrylamides (9 and 10) depending on the structures of the substrates. The route provides a simple method of preparing 6-methoxy- (7e), 8-methoxy- (7d), 6,8-dimethoxy- (7f), and 8,9-dimethoxy-N-methyl-1,2-dihydrobenz-[c]azepin-3-ones (7g), although the scope is limited by some side reactions.

Published
2002

11. Thermal Cycloaddition of Aroylketene to 1-Aryl-1-trimethylsilyloxyethylene: A Simple Synthesis of 2,6-Diaryl-4H-pyran-4-one

Author

Jun Toda, Takehiro Sano, and Toshiaki Saitoh

Subjects
Pharmacology, chemistry.chemical_classification, Aryl, Organic Chemistry, Decarbonylation, Regioselectivity, Medicinal chemistry, Cycloaddition, Analytical Chemistry, chemistry.chemical_compound, chemistry, Pyran, Enol ether, Pyrolytic carbon, Thermal reaction
Abstract

Aroylketene (2) generated by pyrolytic decarbonylation of 5-aryl-2,3-dihydro-2,3-furandione (1) reacted with 1-aryl-1-trimethylsilyloxyethylene (3) in a regioselective manner to give 2,6-diaryl-4H-pyran-4-one (5) and/or 1,5-diarylpentane-1,3,5-trione (6). This reaction provides a simple synthetic method of 2,6-diaryl-4H-pyran-4-one with various substituents in the aryl group

Published
1993

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