Catalysts of the type [Rhfchiral diphosphine)]+ convert 4-substituted 4-pentenals into the corresponding 3-substituted cyclopentanones with generally high turnover numbers and frequencies at 25°C. The enantioselectivities of various substituted 4-pentenals with two chiral diphosphines have been explored. It was found that with the binap catalyst, almost complete enantioselectivity is observed for 4-pentenal substrates bearing 4-substituted tertiary substituents and for ester groups. Ketonic substituents give very high enantioselectivities. The mechanism of intramolecular hydroacylation has been explored, and it is suggested that an important consideration for obtaining high turnover frequencies is related to the acyl-alkyl reductive elimination mechanism which is inferred to occur by a process similar to ester hydrolysis. The origin of the enantioselection is discussed in terms of the interactions between the phenyl groups of the phosphine and the substituent of the pentenal.Intramolecular hydroacylation is one of the more attractive catalytic processes because it converts a pentenal to a cyclic ketone (eq 1). The process is unusual in that the events leading to the product appear to involve scission of the acyl-hydrogen bond to give a hydrido-acyl intermediate followed by the addition of the two fragments to the double bond. With rhodium-based catalysts, 5-membered ring products are almost always produced.The discovery of Tsuji1 that Wilkinson's catalyst, [Rh(PPh3)3-Cl], was capable of decarbonylating aldehydes to form the alkane and the carbonylated complex, trans-[Rh(PPh3)2(CO)Cl], suggested that oxidative addition across the acyl-hydrogen bond was a step in the decarbonylation. Such a hydrido-acyl intermediate could, in principle, hydroacylate a double bond, provided that the rate of hydroacylation was faster than the decarbonylation rate.The first example of intramolecular hydroacylation of 4-pentenals was reported by Sakai,2 who used Wilkinson's catalyst.Stoichiometric amounts of [RhCPPhs^Cl] and the pentenal were used, and only a 30% yield of the desired cyclopentanone was obtained. The remainder of the material was composed of decarbonylation products. Subsequently, Miller3 showed that the [RhfPPhs^Cl] complex could act as a catalyst under ethylene pressure, and Larock4 explored the catalysis with a variety of substrates and with catalysts incorporating differently substituted unidentate triarylphosphines. In neither study were more than a few turnovers observed before all of the catalyst was converted

Background:We developed a computational model integrating clinical data and imaging features extracted from contrast-enhanced computed tomography (CECT) images, to predict lymph node (LN) metastasis in patients with pancreatic ductal adenocarcinoma (PDAC).Methods: This retrospective study included 159 patients with PDAC (118 in the primary cohort and 41 in the validation cohort) who underwent preoperative contrast-enhanced computed tomography examination between 2012 and 2015. All patients underwent surgery and lymph node status was determined. A total of 2041 radiomics features were extracted from venous phase images in the primary cohort, and optimal features were extracted to construct a radiomics signature. A combined prediction model was built by incorporating the radiomics signature and clinical characteristics selected by using multivariable logistic regression. Clinical prediction models were generated and used to evaluate both cohorts. Results: Fifteen features were selected for constructing the radiomics signature based on the primary cohort. The combined prediction model for identifying preoperative lymph node metastasis reached a better discrimination power than the clinical prediction model, with an area under the curve of 0.944 vs. 0.666 in the primary cohort, and 0.912 vs. 0.713 in the validation cohort.Conclusions: This pilot study demonstrated that a noninvasive radiomics signature extracted from contrastenhanced computed tomography imaging can be conveniently used for preoperative prediction of lymph node metastasis in patients with PDAC.

Treatment of (η6-naphthalene)(η4-1,5-cyclooctadiene)ruthenium(0), Ru(η6-C10H8)(η4-1,5-C8H12) (1), with a slight excess of trimethylphosphine, triethylphosphine, trimethyl phosphite, triethyl phosphite, or tert-butyl isocyanide below room temperature gives η4-naphthalene complexes Ru(η4-C10H8)(η4-1,5-C8H12)(L) [L = PMe3 (3), PEt3 (4), P(OMe)3 (5), P(OEt)3 (6), t-BuNC (7)], which provide the first examples of the often postulated η6 to η4 transformation of naphthalene induced by two-electron donor ligands. The η4-naphthalene is easily displaced by an excess of the ligands to give RuL3(η4-1,5-C8H12). At room temperature, complex 1 reacts with a deficiency of PMe3, PEt3, or P(OMe)3 to give binuclear complexes containing bridging naphthalene, (η4-1,5-C8H12)Ru(μ-η6:η4-C10H8)Ru(η4-1,5-C8H12)(L) [L = PMe3 (8), PEt3 (9), P(OMe)3 (10)]. Single-crystal X-ray studies of complexes 3, 4, 5, 9, and 10 show the presence in each case of a folded naphthalene ring with a hinge angle of ca. 40°. In 9 and 10 the metal atoms adopt an anti arrangement relative to the bridging naphthalene.

Treatment of [Ru(η6-C10H8)(η4-1,5-COD)] (1) with excess butadiene at room temperature produces supine,prone-[Ru(η3:η3-2,6-octadiene-1,8-diyl)(η4-1,5-COD)] (supine,prone-2). Similar treatment of 1 with isoprene and (E)- and (Z)-1,3-pentadiene also gives the corresponding analogues of supine,prone- 2, while 2,3-dimethylbutadiene does not react. A low-temperature NMR study of the reaction of 1 with butadiene shows initial formation of [Ru(η4-cisoid-butadiene)(η2-transoid-butadiene)(η4-1,5-COD)] (5) as an intermediate, which is spontaneously converted into supine,prone- 2 upon warming to room temperature. Similarly, treatment of 1 with (E)-1,3-pentadiene gives two intermediates, [Ru{η4-(E)-cisoid-1,3-pentadiene}{η2-(E)-transoid-1,3-pentadiene}(η4-1,5-COD)] (E- 6) and [Ru{η4-(Z)-cisoid-1,3-pentadiene}{η2-(E)-transoid-1,3-pentadiene}(η4-1,5-COD)] (Z- 6), in 44/56 ratio at −50 °C. These intermediates are converted into anti-supine,syn-prone-[Ru(η3:η3-3,7-decadiene-2,9-diyl)(η4-1,5-COD)] (anti-supine,syn-prone- 4). The observed stereochemistries can be explained by a mechanism that involves oxidative coupling between η4-(Z)-cisoid-1,3-pentadiene and η2-(E)-transoid-1,3-pentadiene in Z- 6.