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71.
Fulvenes (1) react with 3,6-dicarbomethoxy-1,2,4,5-tetrazine (2) to give 4a,5-dihydro-2H-cyclopenta[d]pyridazines (3), which can be transformed with mangandioxide to the dehydrocompounds 4. Through 1,6-addition of hydrogen pseudoazaazulenes of the 2H-cyclopenta[d]pyridazin type (6) are obtained. Oxidative C-C-connection of these compounds yields dehydrodimers (10), which on hydrogenation give bis-pseudoazaazulenes (11). 相似文献
72.
Let G[H] denote the composition of the graphs G and H. If G can be decomposed into one-factors and two-factors, H can be decomposed into one-factors, and H is not the empty graph on an odd number of vertices, then G[H] can be decomposed into one-factors. 相似文献
73.
The crystal structures of four peri-naphthalene derivatives model the Felkin–Anh approach of a nucleophilic centre (OH or NMe2) to a carbonyl group attached to a stereogenic centre bearing a large (phenyl), medium (methyl) and a small (hydrogen) group. Thus, the conformation about the (O=)C−C* bond directs the phenyl group approximately perpendicular to the carbonyl group and away from the nucleophile, whose line of approach lies close to the hydrogen atom attached to the stereogenic centre. The nucleophile approaches the carbonyl group at 102.99(11)-112.34(9)° (for NMe2) and at 118.56(14)° (for OH). The small pyramidalization of the carbonyl carbon towards the nucleophile increases as the nucleophilic centre approaches closer. 相似文献
74.
Wang J Onions S Pilkington M Stoeckli-Evans H Halfpenny JC Wallis JD 《Chemical communications (Cambridge, England)》2007,(35):3628-3630
A Co(II) quaterpyridine-type complex has been prepared via a one-pot transformation of a 2,2'-bipyridine Schiff-base ligand in the presence of a Lewis acidic metal salt. 相似文献
75.
This study aims to analyse RDS heavy metal concentrations on road deposited sediment (RDS) using Riccarton Campus of Heriot-Watt
University, Edinburgh, Scotland as a study site. RDS samples were collected at two transverse positions from different sites
over a 4 month period in order to describe the influence of traffic on heavy metal emissions. The heavy metal concentrations
of the RDS were determined by strong nitric acid digestion and atomic absorption spectrometry. The mean concentrations for
Zn, Cu, Cd, Cr, Ni, Pb and Fe were found to be 213, 57, 1, 16, 15, 118, and 13497 mg kg-1 from samples near to the curb and
211, 79, 2, 15, 9, 35, and 14276 mg kg−1 from samples 1 m from the curb respectively. Furthermore for both positions the highest concentrations for all metals were
associated with the finer fraction (<63 μm) and stronger correlations between the metals were found further from the curb
than near the curb, indicating that metals accumulating on the road surface further from the curb may likely be from the same
source (traffic), while the sources of metals near the curb are more diverse. 相似文献
76.
77.
Osten KM Yu I Duffy IR Lagaditis PO Yu JC Wallis CJ Mehrkhodavandi P 《Dalton transactions (Cambridge, England : 2003)》2012,41(26):8123-8134
Functionalized diaminophenols, H(N(R1R2)N(R3)O), were investigated as ligands for indium catalysts in the ring-opening polymerization of racemic lactide. Precursor complexes (N(Me2)N(Me)O)InCl(2) (1), (N(Pr2)NO)InCl(2) (2), and (N(Mes)NO)InCl(2) (3) were synthesized and fully characterized by (1)H and (13)C NMR spectroscopy, elemental analysis, and single-crystal X-ray crystallography. Complexes 1 and 2 were used to synthesize alkoxy-bridged complexes [(N(Me2)N(Me)O)InCl](2)(μ-Cl)(μ-OEt) (4) and [(N(Pr2)NO)InCl](2)(μ-Cl)(μ-OEt) (5). These complexes catalysed the polymerization of racemic lactide at different rates, with complex 5 being substantially more active than complex 4. The dissociation behaviour of these catalysts in the presence of lactide was also studied and used to make comparisons with previously reported catalyst systems. 相似文献
78.
Jennifer Seberry Wallis 《Linear and Multilinear Algebra》2013,61(3):197-207
Recent advances in the construction of Hadamard matrices have depeaded on the existence of Baumert-Hall arrays and four (1, ?1) matrices A B C Dof order m which are of Williamson type, that is they pair-wise satisfy i) MNT = NMT , ∈ {A B C D} and ii) AAT + BBT + CCT + DDT = 4mIm . It is shown that Williamson type matrices exist for the orders m = s(4 ? 1)m = s(4s + 3) for s∈ {1, 3, 5, …, 25} and also for m = 93. This gives Williamson matrices for several new orders including 33, 95,189. These results mean there are Hadamard matrices of order i) 4s(4s ?1)t, 20s(4s ? 1)t,s ∈ {1, 3, 5, …, 25}; ii) 4s(4:s + 3)t, 20s(4s + 3)t s ∈ {1, 3, 5, …, 25}; iii) 4.93t, 20.93t for t ∈ {1, 3, 5, … , 61} ∪ {1 + 2 a 10 b 26 c a b c nonnegative integers}, which are new infinite families. Also, it is shown by considering eight-Williamson-type matrices, that there exist Hadamard matrices of order 4(p + 1)(2p + l)r and 4(p + l)(2p + 5)r when p ≡ 1 (mod 4) is a prime power, 8ris the order of a Plotkin array, and, in the second case 2p + 6 is the order of a symmetric Hadamard matrix. These classes are new. 相似文献
79.
Ryan A. Hemming Megan Bell Liam J. Duffy Jonathan Bristow John D. Wallis Steven M. Allin Philip C. Bulman Page 《Tetrahedron》2019,75(1):121-127
A new, versatile and highly stereoselective approach for the synthesis of non-racemic 3-substituted isoindolin-1-ones is described from a readily available chiral template. The potential of this new protocol is demonstrated through the synthesis of an enantiomerically enriched 3-alkyl N-H isoindolin-1-one target with an e.e. of 98%. 相似文献
80.