- Palladium-Nanoparticles-Catalyzed Oxidative Annulation of Benzamides with Alkynes for the Synthesis of Isoquinolones
-
A novel method to synthesize isoquinolones via oxidative annulation of N-alkoxy benzamides and alkynes using binaphthyl-stabilized palladium nanoparticles (Pd-BNP) as catalyst has been developed. This methodology affords various isoquinolone derivatives in good to excellent yields with high regioselectivities in the presence of air as oxidant. N-Methoxybenzothioamide was also found to undergo oxidative annulation with alkyne successfully and provided a sulfur analogue of isoquinolones in moderate yields. The Pd-BNP catalyst was easily recovered and reused up to four times without any apparent agglomeration. (Figure presented.).
- Sharma, Nidhi,Saha, Rajib,Parveen, Naziya,Sekar, Govindasamy
-
supporting information
p. 1947 - 1958
(2017/06/09)
-
- Formation of an alkyne during degradation of metal-alkylidyne complexes
-
The compound [(Ot-Bu)3WCt-Bu] (1) (t-Bu = C(CH3) 3) decomposes upon contact with water and several organic products are formed, including di-tert-butylacetylene, t-BuCCt-Bu. This process is reminiscent of the degradation of trinuclear metal-alkylidyne complexes in which free carbynes are ejected into solution, couple and form alkynes along with many other products. The reactivity pattern of the resulting t-BuC carbynes that includes extensive hydrogen abstraction, cleavage of alkynes and lack of reactivity towards alkenes is indicative of a quartet (S = 3/2) spin state. A similar spin state was assigned to other RC (R = alkyl) species that were produced by degrading M3-alkylidyne (M = transition metal) complexes in water. t-BuCCt-Bu is also produced during thermal decomposition of solid 1. In 1977 Fischer and co-workers reported a very similar process in which solids of Br(CO)4CrCR1 and Br(CO)4CrCR2 were co-thermolyzed to produce R1CCR2, R 1CCR1, and R2CCR2. Fischer had considered the involvement of free carbynes in the making of the alkynes but later resorted to other explanations. The current results suggest that his original proposal is indeed valid.
- Levy, Ophir,Musa, Sanaa,Bino, Avi
-
p. 12248 - 12251
(2013/09/02)
-
- Directed synthesis of phosphorus-carbon cage compounds - A challenge in organophosphorus chemistry [1]
-
Reactions of the zirconium complexes 2 with hexachloroethane lead to the tetraphosphacubanes 4 whereas extrusion of the Cp2Zr units by means of (Ph3P)2NiCl2 gives rise to the tetraphosphacyclooctadienes 7. Polycyclic phosphorus-carbon systems such as 11 or 14 and 13 are accessible from multi-step reactions of the phosphaalkyne 5 (R = t-Bu) with dienes 9 or tropone (10), respectively. The complex 16 obtained from the spirocyclotrimerization of the phosphaalkyne 5 (R = t-Bu) with aluminum trichloride provides the starting point for the construction of the bis(homo)prismane 19 and the hexaphosphapentaprismane 20. Furthermore, the phosphorus-carbon-aluminum cage compounds 12, 23, and 24 have been prepared from the phosphaalkynes 5 and the triorganoaluminum reagents 22.
- Regitz,Weitling,F?ssler,Breit,Geissler,Julino,Hoffmann,Bergstr?sser
-
p. 425 - 428
(2007/10/03)
-
- Small Rings, 89. - An Alternative Synthesis of Tetra-tert-butyltetrahedrane
-
Cyclopropenyldiazomethane 3 is an ideal precursor for tetra-tert-butyltetrahedrane (6).Both, photochemical and thermal decomposition of 3 lead to cyclobutadiene 7, which can be photoisomerized to tetrahedrane 6.Tetra-tert-butyltetrahedrane (6) is also formed directly by a cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in carbene 4.This is the first example for the synthesis of a tetrahedrane, which does not occur via the corresponding cyclobutadiene.The formation of pyridazine 10 dominates the thermolysis of 3.Azete 12 is obtained both by photolysis as well as by thermolysis of Dewar-pyridazine 11, the irradiation product of 10. - Key Words: Cyclobutadiene / Tetrahedrane / Azete / Cyclopropenyldiazomethane / Valence isomers of pyridazine
- Maier, Guenther,Fleischer, Frank
-
p. 169 - 172
(2007/10/02)
-
- Small Rings, 90. - Peralkyl-Substituted Tetrahedranes
-
Photolysis of the diazo compounds 4a, b generates adamantyltri-tert-butyltetrahedrane (9a) and tri-tert-butylisopropyltetrahedrane (9b), and the corresponding cyclobutadienes 10a, b.In contrast to tetrahedrane 9a, which results from an intramolecular addition in carbene 7a and also from photoisomerization of cyclobutadiene 10a, the only source for tetrahedrane 9b is the cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in the photochemically produced carbene 7b.Tetrahedrane 9b is remarkable in its kinetic and thermal instability, which is caused by the reduced "corset effect" in this compoound.An additional access to this tetrahedrane is possible via the diazomethanes 34A and 34B.The pyridazines 17b and 41, which are formed by thermolysis of the diazo compounds 4b, 34A and 34B lead to the azetes 19 and 43.Last but not least 17b and 41 are interesting molecules themselves because of their inherent chirality. - Key Words: Tetrahedranes / Cyclobutadienes / Azetes / Cyclopropenyldiazomethanes / Pyridazines: chirality, ring inversion, valence isomers
- Maier, Guenther,Fleischer, Frank,Kalinowski, Hans-Otto
-
p. 173 - 186
(2007/10/02)
-
- Small Rings, 78. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)tetrahedrane
-
The chemistry of diazo(1,2,3-tri-tert-butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse.Upon irradiation it fragments exclusively into the acetylenes 7 and 8.Flash thermolysis, on the other hand, gives - aside from the two acetylenes - tri-tert-butylazete (10) and trimethylsilyl cyanide (11).Upon heating 6 presumbaly isomerizes via betaine 17 to Dewar-diazabenzene 13 - which is split into 10 and 11 - and diazabenzvalene 18.This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16. - The CuCl-catalyzed thermal decomposition again follows a different route.Under these conditions tri-tert-butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex.Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated.Upon irradiation of 5 a quantitative isomerization to tri-tert-butyl(trimethylsilyl)tetrahedrane (29) occurs.This second, spectroscopically unequivocally confirmed tetrahedrane melts at 179 deg C.In solution the isomerization to cyclobutadiene 5 starts at about 160 deg C.That means, it is thermally even more stable than tetra-tert-butyltetrahedrane. - Key Words: Diazo compounds / Transition-metal complexes / Photoisomerization / Homocyclopropenylium ions
- Maier, Guenther,Born, Dieter,Bauer, Ines,Wolf, Reinhard,Boese, Roland,Cremer, Dieter
-
p. 173 - 190
(2007/10/02)
-
- Small Rings, 79. - Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and Tetrahedranes
-
The cyclobutadienes 2b,d as well as the corresponding tetrahedranes 3b,d have been prepared according to the "Masamune route" by starting from the diazo compounds 1b,d.Low temperature 13C-NMR measurements of the cyclobutadienes 2a,b,d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes.Fluorodesilylation of 3d probably proceeds via tri-tert-butyltetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18.Reaction of tetrahedrane 3d with LiAlH4 in boiling THF leads to tetrahedrane 3e, which is much less stable than all previously known tetrahedrane derivatives. - Key Words: Diazo compounds / Valence isomerization / "Corset effect", limits of
- Maier, Guenther,Wolf, Reinhard,Kalinowski, Hans-Otto,Boese, Roland
-
p. 191 - 200
(2007/10/02)
-
- -
-
Diazocompound 1 turns out to be the ideal photochemical precursor for tetrahedrane 3. Upon thermolysis Dewarpyridazine 6 is fragmented quantitatively into tri-tert-butylazete 8 and pivalonitrile 9.
- Maier, Guenther,Fleischer, Frank
-
-
- Syntheses with Cyclobutadienes, 19. - Ring Opening of Bi- and Tricyclic Adducts of Carbonyl Compounds onto a Kinetically Stabilized Cyclobutadiene
-
Benzophenone (6) adds photochemically onto the cyclobutadiene 5b to give the oxabicyclohexene 7 which is in equilibrium with the oxatricyclohexane 8 in acidic medium.The reaction of fluorenone (11) with 5b is comparable (formation of 12 and 13) but the bicyclic compound undergoes spontaneous ring opening reaction to the 1,3-diene 14.The latter one isomerizes photochemically by electrocyclic ring closure to the cyclobutene 15; this process is reversible thermally.The cyclopropenone 16 only reacts slowly at room temperature with 5b; instead of the primary adduct 17 the isomeric trifulvene 18 is isolated.Under the influence of trifluoroacetic acid the oxabicyclohexenes (7->19,21a,c,d->22a,c,d) as well as the oxatricyclohexanes (8->19, 13->14) undergoing ring opening reactions to the corresponding 1,3-dienes.Crystal structure analyses have been performed for 18 and 22a.
- Fink, Juergen,Guembel, Helmut,Eisenbarth, Philipp,Regitz, Manfred
-
p. 1027 - 1038
(2007/10/02)
-
- HOCHSUBSTITUIERTE TRICYCLOPENTANONE UND CYCLOPROPENYLDIAZOMETHANE - VORSTUFEN FUER TETRAHEDRANE?
-
Reaction of tri-tert-butylcyclopropenylium tetrafluoroborate 7 with the Li-salt of tert-butyldiazomethane leads to the astonishingly stable diazo compound 6.The trimethylsilyl derivative 8 can be prepared via the same route.On photolysis or pyrolysis both
- Maier, Guenter,Reuter, Karl Arnold,Reisenauer, Hans Peter
-
p. 1845 - 1848
(2007/10/02)
-
- SYNTHESIS OF TERTIARY ALKYL-SUBSTITUTED ACETYLENES BY ELECTROPHILIC ADDITION TO SILYLACETYLENES
-
The reaction of silylacetylenes 6-8 with tertiary alkyl halides 11-13 under Lewis acid catalysis affords tertiary alkyl-substituted acetylenes 1-5.The reaction occurs under mild conditions (from -78 to -17 deg C) and requires fairly short times (1-6 h).Se
- Capozzi, Giuseppe,Ottana, Rosaria,Romeo, Giovanni,Marcuzzi, Franco
-
p. 311 - 314
(2007/10/02)
-
- Investigations on Diazo Compounds and Azides, XLIII. 1,2-Dewarpyridazines - Suitable Precursors for the Generation of Azacyclobutadienes?
-
Heating of the (diazomethyl)cyclopropenes 9b and c yields the pyridazines 10b and c as main products.The formation of the carbenes 11b and c, which decompose into the acetylenes 12 and 13, competes with the isomerization reaction.The pyridazine 10d is obtained immediately by electrophilic diazoalkane substitution of 6 with the cyclopropenylium salt 8; 9d can be established as intermediate by IR spectroscopy.The irradiation of the pyridazines 10a-d (10a is described in literature) leads to the stable 1,2-Dewarpyridazines 15a-d.The flash pyrolysis of 15b, conducted exemplarily, affords the fragment pairs 16 and 13b as well as 12 and 20.Their formation is in agreement with the intermediacy of the valence tautomeric azacyclobutadienes 1718.
- Eisenbarth, Philipp,Regitz, Manfred
-
p. 445 - 454
(2007/10/02)
-
- Carbenes, 28. tert-Butyl 2,3,4-Tri-tert-butylcyclobutadiene-1-carboxylate
-
The cyclopropenyldiazoacetate 3a - available from tri-tert-butylcyclopropenylium bromide (1) and the mercury bis(diazoacetate) 2a - is the starting material for the synthesis of the title compound 5a.The carbene 4a, generated photolytically from 3a, is responsible for the formation of both the cyclobutadiene 5a and the acetylenes 6 and 7a.Acetylene formation is also observed in the flash pyrolysis of 3a (formation of 6, 7a, 8, and 9) and 5a (formation of 6, 8, and 9).The extremely air sensitive cyclobutadiene 5a ( -> 16) shows a pronounced cycloaddition behaviour towards dienophiles.With dimethyl ac etylenedicarboxylate, maleic anhydride, cyclopentadiene, diethyl azodicarboxylate and 4-phenyl-1,2,4-triazoline-3,5-dione cycloadducts were isolated (17, 18, 19, 20, 21).The series of the diazadihydro Dewar benzenes is also entered by the reaction of the cyclopropenyldiazoacetates 3 with the triazolinedione; the betaines 22 and 24 are regarded to be intermediates of this reaction.
- Eisenbarth, Philipp,Regitz, Manfred
-
p. 3796 - 3810
(2007/10/02)
-
- Small Rings, 38. Tetra-tert-butyltetrahedrane
-
The first synthesis of a tetrahedrane stabilized by sterically demanding substituents is described.Tetrahedrane 37 originates from irradiation of tetra-tert-butylcyclopentadienone (26), which can be prepared starting from the already known cyclopentadienone 5.It forms colourless stable crystals.At 135 deg C tetrahedrane 37 valenceisomerizes to the corresponding cyclobutadiene 36.This reaction can be reversed photochemically.
- Maier, Guenther,Pfriem, Stephan,Schaefer, Ulrich,Malsch, Klaus-Dieter,Matusch, Rudolf
-
p. 3965 - 3987
(2007/10/02)
-