16 research outputs found
Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination
The possibility of functionalization of dipyrido[3,2-e:2â˛,3â˛-h]acenaphthene containing a quino[7,8-h]quinoline fragment and being a highly basic diazine analog of 1,8-bis(dimethylamino)naphthalene (âproton spongeâ) has been studied for the first time. In addition to the pronounced tendency of the title compound to form associates with an intramolecular hydrogen bond of the NHN type (new examples with the participation of pyridine rings, including self-associates are shown) and its inertness to amination reactions of the pyridine rings, the naphthalene core at positions 5(8) and the CH2CH2 bridge (dehydrogenation) undergo chemical modifications under mild conditions, giving the corresponding acenaphthylenes. The latter can also be obtained in an unusual way by tele-elimination from 5,8-dibromodipyridoacenaphthene by reaction with neutral or anionic bases
SNH Amidation of 5-Nitroisoquinoline: Access to Nitro- and Nitroso Derivatives of Amides and Ureas on the Basis of Isoquinoline
For the first time, amides and ureas based on both 5-nitroisoquinoline and 5-nitrosoisoquinoline were obtained by direct nucleophilic substitution of hydrogen in the 5-nitroisoquinoline molecule. In the case of urea and monosubstituted ureas, only 5-nitrosoisoquinoline-6-amine is formed under anhydrous conditions
Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Đ)-ones with a terminal phenanthroline group
A series of novel photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Đ)-ones with a terminal phenanthroline receptor substituent was synthesized. Upon irradiation in acetonitrile or DMSO with light of 436 nm, they underwent ZâE isomerization of the C=C bond, followed by very fast NâO migration of the acyl group and the formation of nonemissive O-acylated isomers. These isomers were isolated preparatively and fully characterized by IR, 1H, and 13C NMR spectroscopy as well as HRMS and XRD methods. The reverse thermal reaction was catalyzed by protonic acids. N-Acylated compounds exclusively with Fe2+ formed nonfluorescent complexes with a contrast naked-eye effect: a color change of the solutions from yellow to dark orange. Subsequent selective interaction with AcOâ led to the restoration of the initial absorption and emission properties. Thus, the obtained compounds represent dual-mode âonâoffâonâ switches of optical and fluorescent properties under sequential exposure to light and H+ or sequential addition of Fe2+ and AcOâ ions
Divergent Transformations of 2âNitroâ1<i>H</i>âbenzo[<i>f</i>]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1â<i>b</i>]furans via Base-Mediated Pyran Ring Contraction
The action of 2-(1-arylethylidene)malononitriles
on 2-nitro-1H-benzo[f]chromenes
in the presence of
Et3N and MoO3¡2H2O results in
naphtho[2,1-b]furans containing an allylidenemalononitrile
unit in the Îą-position. The reaction proceeds with contraction
of the pyran ring via a cascade carba-Michael addition/retro-oxa-Michael
reaction/tautomerization/SN2/oxidation process. In contrast,
the reaction of 2-nitro-1H-benzo[f]chromenes with the cyclic Knoevenagel adduct derived from 1-indanone
and malononitrile leads to dihydroindeno[1,2-c]xanthenes.
The possibility of further transformations of naphtho[2,1-b]furan derivatives as useful precursors and their optical
properties were also investigated
Organometallic Synthesis of 2,3,6,7-Tetrasubstituted 1,8-Bis(dimethylamino)naphthalenes for Investigation of the Double Buttressing Effect in Proton Sponges
The lithiation of 2,7-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene
(DMAN, proton sponge) bearing potentially ortho-directing
OMe, NMe2, and SMe groups was studied. It has been shown
that OMe groups facilitate selective dual β-lithiation of the
naphthalene moiety while the 2(7)-NMe2 groups allow only
monolithiation presumably due to the decreased acidity of the ring
CâH bonds and conformational immobilization after coordination
to the lithium atom. In contrast, the SMe groups provided no ring
lithiation and underwent deprotonation of their methyl fragment. The
first representatives of previously unknown 2,3,6,7-tetrasubstituted
DMANs have been synthesized in good yield after treatment of 2,7-dimethoxy-3,6-dilithio
DMAN with the appropriate electrophiles (MeI, Me2S2, Me3SiCl, DMF, etc.). Because the exceedingly
high basicity of 2,7-dimethoxy DMAN is commonly attributed to the
so-called âbuttressing effectâ (BE), the availability
of 2,3,6,7-tetrasubstituted species provided the first opportunity
to study the double BE version. Using X-ray diffraction and basicity
measurements, we showed that due to the high conformational mobility
of the methoxy groups, the most striking manifestations of double
BE are the strong planarization of peri-NMe2 groups and a significant decrease in basicity, while the length
and the other properties of the intramolecular NHN hydrogen bond in
the corresponding protonated species undergo minor changes
Organometallic Synthesis of 2,3,6,7-Tetrasubstituted 1,8-Bis(dimethylamino)naphthalenes for Investigation of the Double Buttressing Effect in Proton Sponges
The lithiation of 2,7-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene
(DMAN, proton sponge) bearing potentially ortho-directing
OMe, NMe2, and SMe groups was studied. It has been shown
that OMe groups facilitate selective dual β-lithiation of the
naphthalene moiety while the 2(7)-NMe2 groups allow only
monolithiation presumably due to the decreased acidity of the ring
CâH bonds and conformational immobilization after coordination
to the lithium atom. In contrast, the SMe groups provided no ring
lithiation and underwent deprotonation of their methyl fragment. The
first representatives of previously unknown 2,3,6,7-tetrasubstituted
DMANs have been synthesized in good yield after treatment of 2,7-dimethoxy-3,6-dilithio
DMAN with the appropriate electrophiles (MeI, Me2S2, Me3SiCl, DMF, etc.). Because the exceedingly
high basicity of 2,7-dimethoxy DMAN is commonly attributed to the
so-called âbuttressing effectâ (BE), the availability
of 2,3,6,7-tetrasubstituted species provided the first opportunity
to study the double BE version. Using X-ray diffraction and basicity
measurements, we showed that due to the high conformational mobility
of the methoxy groups, the most striking manifestations of double
BE are the strong planarization of peri-NMe2 groups and a significant decrease in basicity, while the length
and the other properties of the intramolecular NHN hydrogen bond in
the corresponding protonated species undergo minor changes