Facile route to dihydroindacene type ligands using multiple Heck reactions on aryl polybromides

Reaction of aryl di-, tri-, or tetrabromides with arylboronic acids or alkenes in the presence of a palladium-tetraphosphine catalyst

“…In recent years, the ligand P(t-Bu) 3 has also been successfully tested with these substrates [13,14]. With this ligand good results have been reported by Crociani and co-workers [13] for Heck reaction on dibromobenzene derivatives. Hollow palladium spheres also efficiently catalyses Suzuki reaction in the presence of 1,4-diiodobenzene [15].…”

“…The reaction also proceeds with Pd(OAc) 2 without added ligand [12]. In recent years, the ligand P(t-Bu) 3 has also been successfully tested with these substrates [13,14]. With this ligand good results have been reported by Crociani and co-workers [13] for Heck reaction on dibromobenzene derivatives.…”

An Improved Synthesis of 3,6-Dihydro-as-indacene

“…The bond distances for C(1)-C(2) and C(9)-C(10) are 1.3352(16) Å and 1.3366(15) Å, respectively, and are very close to that of a standard double bond, indicating that they are localized double bonds. In comparison, the bond distances for C(1)-C(12), C(2)-C(3), C(3)-C(4), C(7)-C(8), C(8)-C(9) and C(10)-C(11) [1.4600 (14), 1.4993(18), 1.5077(15), 1.5058 (14), 1.5019 (16) and 1.4624 (13), respectively] correspond to single bonds, in agreement with the symmetry observed in the NMR analysis. On the other hand, the torsion angles at the hinges [i.e., 1.46(19)°, defined by C1, C12, C11 and C10] are about 1° (Table 2), being similar to those of the benzene In summary, we have simplified the Katz original synthesis 1a of dihydro-as-indacene by incorporating several improvements for the preparation of some of the intermediates (as carried out by other investigators with different research purposes).…”

“…2 In recent decades there has been growing interest in the synthesis of such species, since they can result in interesting cooperative effects, as well as novel electronic, magnetic and optical properties. [3][4][5][6][7][8] In contrast to dihydro-s-indacene, where along with the non-substituted hydrocarbon, 9 several alkylated derivatives are also known, [10][11][12][13] the lack of an efficient synthetic procedure for dihydro-as-indacene, 1 as well as the reduced number of known alkylated derivatives, 10,14 has resulted in a rather slow development of its chemistry, despite the fact that the synthesis of the non-substituted compound was reported by Katz in 1968. 1a The Katz synthesis is relatively tedious, and at the time of its publication the characterization of the product was poor, 1a mainly because NMR spectroscopy had not been developed to the extent it has today.…”

Size-dependent effects in supported highly dispersed Fe2O3 catalysts, doped with Pt and Pd

“…The use of less expensive transition metal oxides allows the preparation of catalysts with higher active phase loading [3,4]. The investigation of transition metal oxidenoble metal supported catalysts is a question of theoretical and practical interest, because of the expected synergic effect between the components and improvement of their catalytic performance in the oxidation of hydrocarbons [5].…”