“…457 For comparison, in 1,2-diisopropyl-3,4,5,6-tetracyclopropylbenzene, which was prepared by cotrimerization of diisopropylacetylene and dicyclopropylacetylene (565) under catalysis with Hg[Co-(CO) 4 ] 2 , the four cyclopropyl groups adopt the same conformation with C ar -C ar -C cycl -H torsional angles close to 90°, whereas the two isopropyl groups maintain a bisected orientation. 458 Upon careful reinvestigation of the thermal reaction of 565 with Fe 3 (CO) 12 under almost the same conditions as previously reported 456 (4 h of heating), the known 455 tetracyclopropyl-p-benzoquinone (650) (3%) and the previously unknown tricarbonyl(tetracyclopropylcyclobutadiene)iron (651-H) (1%), along with the previously described products 648 (48%) and 649 (18%), were isolated (Scheme 113). 459 Under the same conditions, the reaction of bis(1-methylcyclopropyl)ethyne (621) with Fe 3 (CO) 12 yielded neither any of the peralkylated cyclopentadienone complex nor the corresponding benzene or benzoquinone derivatives.…”
“…Heating of 647 in toluene furnished tricarbonyl(tetracyclopropylcyclopentadienone)iron (648) in 45% yield. 455 The latter was prepared directly from 565 by heating with Fe 3 (CO) 12 at 180°C in 30% yield along with hexacyclopropylbenzene (649) (20% yield). 456 In the crystal, 649 disclosed an unusual conformation of D 3d symmetry in which the cyclopropyl substituents are alternatingly oriented up and down with respect to the central six-membered ring (Scheme 113); thus no conjugative interaction between the six cyclopropyl groups and the π-system of the aromatic ring is possible.…”
“…Thus, heating or irradiation of 565 with Fe 2 (CO) 9 or Fe(CO) 5 , respectively, produced the dinuclear complex 647 in 47% and 42% yield, respectively, along with seven minor products. Heating of 647 in toluene furnished tricarbonyl(tetracyclopropylcyclopentadienone)iron ( 648 ) in 45% yield . The latter was prepared directly from 565 by heating with Fe 3 (CO) 12 at 180 °C in 30% yield along with hexacyclopropylbenzene ( 649 ) (20% yield) .…”
Section: 2 Oligocyclopropyl-substituted Carbo- and
Heterocyclesmentioning
“…457 For comparison, in 1,2-diisopropyl-3,4,5,6-tetracyclopropylbenzene, which was prepared by cotrimerization of diisopropylacetylene and dicyclopropylacetylene (565) under catalysis with Hg[Co-(CO) 4 ] 2 , the four cyclopropyl groups adopt the same conformation with C ar -C ar -C cycl -H torsional angles close to 90°, whereas the two isopropyl groups maintain a bisected orientation. 458 Upon careful reinvestigation of the thermal reaction of 565 with Fe 3 (CO) 12 under almost the same conditions as previously reported 456 (4 h of heating), the known 455 tetracyclopropyl-p-benzoquinone (650) (3%) and the previously unknown tricarbonyl(tetracyclopropylcyclobutadiene)iron (651-H) (1%), along with the previously described products 648 (48%) and 649 (18%), were isolated (Scheme 113). 459 Under the same conditions, the reaction of bis(1-methylcyclopropyl)ethyne (621) with Fe 3 (CO) 12 yielded neither any of the peralkylated cyclopentadienone complex nor the corresponding benzene or benzoquinone derivatives.…”
“…Heating of 647 in toluene furnished tricarbonyl(tetracyclopropylcyclopentadienone)iron (648) in 45% yield. 455 The latter was prepared directly from 565 by heating with Fe 3 (CO) 12 at 180°C in 30% yield along with hexacyclopropylbenzene (649) (20% yield). 456 In the crystal, 649 disclosed an unusual conformation of D 3d symmetry in which the cyclopropyl substituents are alternatingly oriented up and down with respect to the central six-membered ring (Scheme 113); thus no conjugative interaction between the six cyclopropyl groups and the π-system of the aromatic ring is possible.…”
“…Thus, heating or irradiation of 565 with Fe 2 (CO) 9 or Fe(CO) 5 , respectively, produced the dinuclear complex 647 in 47% and 42% yield, respectively, along with seven minor products. Heating of 647 in toluene furnished tricarbonyl(tetracyclopropylcyclopentadienone)iron ( 648 ) in 45% yield . The latter was prepared directly from 565 by heating with Fe 3 (CO) 12 at 180 °C in 30% yield along with hexacyclopropylbenzene ( 649 ) (20% yield) .…”
Section: 2 Oligocyclopropyl-substituted Carbo- and
Heterocyclesmentioning
“… Dicyclopropylacetylene as a multi-π-electron ligand. Adding extra unsaturation to the original C-C π-linkage was shown [ 237 , 238 ] to render the cyclopropyl group inert to attack by iron carbonyl. For example, photoreaction of cyclopropylacetylene 80 with Fe(CO) 5 gave rise to benzoquinones 81 and 82 originating from the insertion of carbonyls between the molecules of acetylene while leaving the cyclopropane ring itself intact [ 237 ].…”
Section: Iron-catalyzed Synthesis and Some Reactions Of Cyclopropamentioning
The objective of this review is to provide a current overview of the rapidly developing chemistry of organometallic complexes and particularly organoiron complexes useful in asymmetric and stereoselective reactions. Also covered are stereoselective reactions of α, β-unsaturated acyl ligands bound to the chiral auxiliary [(η5-C5H5) Fe(CO)(PPh3)] and new applications of organoiron complexes in the synthesis of natural products. The mechanistic aspects and stabilizing effects of the Fe(CO)3 group for alkenes or conjugated dienes are discussed. A brief summary of recent work on the special role of iron in biological reactions is also included.
Durch Bestrahlung von Dicyclopropylacetylen (I) in Gegenwart von F e(CO) 5 in Hexan entstehen die Verbindungen (II)‐(IX) wie im Formelschema angedeutet.
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