- The first proton sponge-based amino acids: Synthesis, acid-base properties and some reactivity
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The first hybrid base constructed from 1,8-bis(dimethylamino)naphthalene (proton sponge or DMAN) and glycine, N-methyl-N-(8-dimethylamino-1-naphthyl)aminoacetic acid, was synthesised in high yield and its hydrobromide was structurally characterised and used to determine the acid-base properties via potentiometric titration. It was found that the basic strength of the DMAN-glycine base (pKa = 11.57, H2O) is on the level of amidine amino acids like arginine and creatine and its structure, zwitterionic vs. neutral, based on the spectroscopic (IR, NMR, mass) and theoretical (DFT) approaches has a strong preference to the zwitterionic form. Unlike glycine, the DMAN-glycine zwitterion is N-chiral and is hydrolytically cleaved with the loss of glycolic acid on heating in DMSO. This reaction together with the mild decarboxylative conversion of proton sponge-based amino acids into 2,3-dihydroperimidinium salts under air-oxygen was monitored with the help of the DMAN-alanine amino acid. The newly devised amino acids are unique as they combine fluorescence, strongly basic and redox-active properties.
- Ozeryanskii, Valery A.,Gorbacheva, Anastasia Yu.,Pozharskii, Alexander F.,Vlasenko, Marina P.,Tereznikov, Alexander Yu.,Chernov'Yants, Margarita S.
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Direct chlorination of 1,8-bis(dimethylamino)naphthalene ("proton sponge") with 1-chlorobenzotriazole gave its 2-chloro and 2,7-dichloro derivatives in high yields. This is the first example of regioseleclive electrophilic ortho-substitution in this series. 4-Chloro and 4,5-dichloro-1,8-bis(dimethylamino)naphthalenes were synthesized by a multistage indirect procedure from the corresponding perimidinium salts.
- Ozeryanskii,Pozharskii,Vistorobskii
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p. 251 - 256
(2007/10/03)
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- Electronic Structure of Heterospirenes-PE Spectroscopic Investigations
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The synthesis of the heterospirenes 1-9 is described and their He I photoelectron (PE) spectra are recorded.The assignment of the first PE bands is based on a comparison with fragment molecules and on molecular orbital calculations using semiempirical methods (PPP, MINDO/3). in the case of 1, 2, 4, and 5 strong spirointeraction has been elucidated.For 3 the analysis of the spectrum is hampered due to the strong overlap of the bands while for 6 the nonplanarity brings about a reduction of spirointeractions.For 7-9 the interaction between both fragments could not be detected.
- Gleiter, Rolf,Uschmann, Joachim
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p. 370 - 380
(2007/10/02)
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- Preparation of a Range of NNN'N'-Tetrasubstituted 1,8-Diaminonaphthalenes
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Alkylation of 1,8-bis(methylamino)naphthalene with difunctional reagents leads to a series of 1,5-dimethylnaphtho-1,5-diazacycloalkanes (1)-(5), to 1,5-dimethylbenzonaphtho-1,5-diazacyclononane (6), and to 1,5-dimethylnaphtho-1,5-diaza-8-oxacyclodecane (7).A variety of attempts to develop a selective preparation of 1,8-bis(methylamino)naphthalene was reported.The preparation of 9,9-dimethylnaphtho-1,5-diazabicyclononane (8), naphtho-1,5-diazabicyclononane (9), and naphtho-1,5-diazabicycloundecane (10) from 1,8-diaminonaphthalene are described.Reaction of appropriate 1,4- and 1,5-dihalides with 1,8-diaminonaphthalene leads to 1,8-bis-(1-pyrrolidinyl)naphthalene (11), 1,8-bis(1,3-dihydroisoindol-2-yl)naphthalene (12), 1,8-bis-(1-piperidinyl)naphthalene (13), and 1,8-dimorpholinonaphthalene (14).Nitration of 2,7-dimethylnaphthalene gives a mixture from which 2,7-dimethyl-1,8-dinitronaphthalene may be isolated; this is reduced and alkylated to give 1,8-bis(dimethylamino)-2,7-dimethylnaphthalene (15). 1,8-Bis(dimethylamino)-2,7-dimethoxynaphthalene (16) and 1,8-bis(diethylamino)-2,7-dimethoxynaphthalene (17) are similarly prepared by reduction and alkylation of 1,8-dinitro-2,7-dimethoxynaphthalene.Reaction of 2,2-dimethyl-1,3-dihydroperimidine with αα'-dibromo-o-xylene led, surprisingly, to (12) and 5-(2-propyl)benzonaphtho-1,5-diazabicyclononane (24).
- Alder, Roger W.,Bryce, Martin R.,Goode, Nigel C.,Miller, Nigel,Owen, Judith
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p. 2840 - 2847
(2007/10/02)
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