The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Ottorino De Lucchi - One of the best experts on this subject based on the ideXlab platform.
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preparation of enantiomerically pure 1 1 binaphthalene 2 2 diol and 1 1 binaphthalene 2 2 dithiol
Journal of Organic Chemistry, 1993Co-Authors: Davide Fabbri, Giovanna Delogu, Ottorino De LucchiAbstract:A practical preparation of enantiomerically pure 1,1'-binaphthalene-2,2'-diol (1) and 1,1'-binaphthalene-2,2'-dithiol (2) is reported. Enantiopure 2 is obtained from enantiopure 1 via Newman-Kwart Rearrangement of the thiocarbamoyl derivative 5 under controlled reaction conditions. The enantiopure starting diol 1 was obtained by a simple and inexpensive method engaging condensation of thiophosphoryl chloride and (S)-(-)-α-methylbenzylamine in pyridine and reaction of the resulting phosphoramidate 3 with racemic binaphthol 1 to give quantitatively a 1:1 mixture of diastereoisomers 4 that were cleanly separated by a single recrystallization from a chloroform-ethanol mixture in very high yield
Petr Zimcik - One of the best experts on this subject based on the ideXlab platform.
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role of steric hindrance in the newman kwart Rearrangement and in the synthesis and photophysical properties of arylsulfanyl tetrapyrazinoporphyrazines
Journal of Organic Chemistry, 2014Co-Authors: Veronika Novakova, Miroslav Miletin, Tereza Filandrova, Juraj Lenco, Ales Růžicka, Petr ZimcikAbstract:Conditions for the Newman-Kwart Rearrangement of phenols into thiophenols were investigated in relation to the bulkiness of substituents at the 2 and 6 positions of the starting phenol derivative with an emphasis on eliminating side reactions. Thiophenols with different 2,6-disubstitution patterns (including hydrogen, methyl, isopropyl or tert-butyl groups) were used for the synthesis of 5,6-bis(arylsulfanyl)pyrazine-2,3-dicarbonitriles that underwent cyclotetramerization leading to the corresponding zinc tetrapyrazinoporphyrazines (TPyzPz), aza-analogues of phthalocyanines. Several methods for the cyclotetramerization were attempted to eliminate problematic side reactions. Magnesium butoxide was found as the most suitable cyclotetramerization agent and afforded TPyzPzs in reasonable yields of approximately 30% under mild conditions. The varying arrangements of the peripheral substitutions resulting from the different bulkiness of the substituents were demonstrated by the X-ray structures of the pyrazine-...
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Role of Steric Hindrance in the Newman-Kwart Rearrangement and in the Synthesis and Photophysical Properties of Arylsulfanyl Tetrapyrazinoporphyrazines
2014Co-Authors: Veronika Novakova, Miroslav Miletin, Tereza Filandrová, Juraj Lenčo, Aleš Růžička, Petr ZimcikAbstract:Conditions for the Newman-Kwart Rearrangement of phenols into thiophenols were investigated in relation to the bulkiness of substituents at the 2 and 6 positions of the starting phenol derivative with an emphasis on eliminating side reactions. Thiophenols with different 2,6-disubstitution patterns (including hydrogen, methyl, isopropyl or tert-butyl groups) were used for the synthesis of 5,6-bis(arylsulfanyl)pyrazine-2,3-dicarbonitriles that underwent cyclotetramerization leading to the corresponding zinc tetrapyrazinoporphyrazines (TPyzPz), aza-analogues of phthalocyanines. Several methods for the cyclotetramerization were attempted to eliminate problematic side reactions. Magnesium butoxide was found as the most suitable cyclotetramerization agent and afforded TPyzPzs in reasonable yields of approximately 30% under mild conditions. The varying arrangements of the peripheral substitutions resulting from the different bulkiness of the substituents were demonstrated by the X-ray structures of the pyrazine-2,3-dicarbonitriles. The prepared zinc arylsulfanyl TPyzPzs showed an absorption maximum at a Q-band over 650 nm, fluorescence quantum yields between 0.078 and 0.20, and singlet oxygen quantum yields ranging 0.58–0.69. TPyzPzs with isopropyl groups were found to be the best derivatives in this series as they combined facile cyclotetramerization, no aggregation, and good photophysical properties, which makes them potentially suitable for photodynamic therapy
Davide Fabbri - One of the best experts on this subject based on the ideXlab platform.
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preparation of enantiomerically pure 1 1 binaphthalene 2 2 diol and 1 1 binaphthalene 2 2 dithiol
Journal of Organic Chemistry, 1993Co-Authors: Davide Fabbri, Giovanna Delogu, Ottorino De LucchiAbstract:A practical preparation of enantiomerically pure 1,1'-binaphthalene-2,2'-diol (1) and 1,1'-binaphthalene-2,2'-dithiol (2) is reported. Enantiopure 2 is obtained from enantiopure 1 via Newman-Kwart Rearrangement of the thiocarbamoyl derivative 5 under controlled reaction conditions. The enantiopure starting diol 1 was obtained by a simple and inexpensive method engaging condensation of thiophosphoryl chloride and (S)-(-)-α-methylbenzylamine in pyridine and reaction of the resulting phosphoramidate 3 with racemic binaphthol 1 to give quantitatively a 1:1 mixture of diastereoisomers 4 that were cleanly separated by a single recrystallization from a chloroform-ethanol mixture in very high yield
Veronika Novakova - One of the best experts on this subject based on the ideXlab platform.
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role of steric hindrance in the newman kwart Rearrangement and in the synthesis and photophysical properties of arylsulfanyl tetrapyrazinoporphyrazines
Journal of Organic Chemistry, 2014Co-Authors: Veronika Novakova, Miroslav Miletin, Tereza Filandrova, Juraj Lenco, Ales Růžicka, Petr ZimcikAbstract:Conditions for the Newman-Kwart Rearrangement of phenols into thiophenols were investigated in relation to the bulkiness of substituents at the 2 and 6 positions of the starting phenol derivative with an emphasis on eliminating side reactions. Thiophenols with different 2,6-disubstitution patterns (including hydrogen, methyl, isopropyl or tert-butyl groups) were used for the synthesis of 5,6-bis(arylsulfanyl)pyrazine-2,3-dicarbonitriles that underwent cyclotetramerization leading to the corresponding zinc tetrapyrazinoporphyrazines (TPyzPz), aza-analogues of phthalocyanines. Several methods for the cyclotetramerization were attempted to eliminate problematic side reactions. Magnesium butoxide was found as the most suitable cyclotetramerization agent and afforded TPyzPzs in reasonable yields of approximately 30% under mild conditions. The varying arrangements of the peripheral substitutions resulting from the different bulkiness of the substituents were demonstrated by the X-ray structures of the pyrazine-...
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Role of Steric Hindrance in the Newman-Kwart Rearrangement and in the Synthesis and Photophysical Properties of Arylsulfanyl Tetrapyrazinoporphyrazines
2014Co-Authors: Veronika Novakova, Miroslav Miletin, Tereza Filandrová, Juraj Lenčo, Aleš Růžička, Petr ZimcikAbstract:Conditions for the Newman-Kwart Rearrangement of phenols into thiophenols were investigated in relation to the bulkiness of substituents at the 2 and 6 positions of the starting phenol derivative with an emphasis on eliminating side reactions. Thiophenols with different 2,6-disubstitution patterns (including hydrogen, methyl, isopropyl or tert-butyl groups) were used for the synthesis of 5,6-bis(arylsulfanyl)pyrazine-2,3-dicarbonitriles that underwent cyclotetramerization leading to the corresponding zinc tetrapyrazinoporphyrazines (TPyzPz), aza-analogues of phthalocyanines. Several methods for the cyclotetramerization were attempted to eliminate problematic side reactions. Magnesium butoxide was found as the most suitable cyclotetramerization agent and afforded TPyzPzs in reasonable yields of approximately 30% under mild conditions. The varying arrangements of the peripheral substitutions resulting from the different bulkiness of the substituents were demonstrated by the X-ray structures of the pyrazine-2,3-dicarbonitriles. The prepared zinc arylsulfanyl TPyzPzs showed an absorption maximum at a Q-band over 650 nm, fluorescence quantum yields between 0.078 and 0.20, and singlet oxygen quantum yields ranging 0.58–0.69. TPyzPzs with isopropyl groups were found to be the best derivatives in this series as they combined facile cyclotetramerization, no aggregation, and good photophysical properties, which makes them potentially suitable for photodynamic therapy
Giovanna Delogu - One of the best experts on this subject based on the ideXlab platform.
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preparation of enantiomerically pure 1 1 binaphthalene 2 2 diol and 1 1 binaphthalene 2 2 dithiol
Journal of Organic Chemistry, 1993Co-Authors: Davide Fabbri, Giovanna Delogu, Ottorino De LucchiAbstract:A practical preparation of enantiomerically pure 1,1'-binaphthalene-2,2'-diol (1) and 1,1'-binaphthalene-2,2'-dithiol (2) is reported. Enantiopure 2 is obtained from enantiopure 1 via Newman-Kwart Rearrangement of the thiocarbamoyl derivative 5 under controlled reaction conditions. The enantiopure starting diol 1 was obtained by a simple and inexpensive method engaging condensation of thiophosphoryl chloride and (S)-(-)-α-methylbenzylamine in pyridine and reaction of the resulting phosphoramidate 3 with racemic binaphthol 1 to give quantitatively a 1:1 mixture of diastereoisomers 4 that were cleanly separated by a single recrystallization from a chloroform-ethanol mixture in very high yield