Search results for "domino"

Permanent Stoma After Low Anterior Resection for Rectal Cancer

2010

BACKGROUND AND OBJECTIVES: A low anterior resection procedure for removing a rectal tumor aims to preserve the sphincter and avoid a permanent stoma. Permanent stomas are primarily necessary in cases of poor anorectal function and local recurrence. The aim of this study was to clarify whether anastomosis-related complications and local recurrence influenced the rate of permanent stomas in a long-term follow-up. METHODS: Of 1032 consecutive patients with rectal cancer, 397 were treated by low anterior resection (R0 and R1 resections) between 1985 and 2007 at the Department of General and Abdominal Surgery of the University Hospital, Mainz (Germany). All patient data were collected prospectiv…

Primary umbilical endometrioma: Analyzing the pathogenesis of endometriosis from an unusual localization

2015

Abstract Objective This report presents a rare case of symptomatic primary umbilical endometriosis and reviews the literature on the topic with the aim to clarify some questions on the origin of endometriosis. Case report A 33-year-old woman with cyclic umbilical bleeding was found to have umbilical endometriosis. She had no history of pelvic or abdominal surgery. There was no past history of endometriosis or endometriosis-associated symptoms. An omphalectomy was performed after explorative laparoscopy to carefully inspect the abdominopelvic cavity and assess any coexisting pelvic endometriotic lesions. Histological examination confirmed the diagnosis of umbilical endometriosis. Conclusion …

Domino Synthesis of 3-Alkyliden-2,3-Dihydro-4-Quinolones

2019

Theoretical study of the molecular mechanism of the domino pathways for squarate ester sequential reactions

1999

Stereoselective Synthesis of Bromopiperidinones and their Conversion to Annulated Heterocycles

2009

N-Galactopyranosyl- and N-glucopyranosyl imines of aliphatic, aromatic and heteroaromatic aldehydes react with 1-methoxy-3-trimethylsilyloxy-1,3-butadiene in a domino Mannich-Michael reaction cascade to give 2-substituted 5,6-dehydro-piperidin-4-ones with high diastereoselectivity. Treatment of these cyclic enaminones with N-bromo-succinimide yields the corresponding 2-substituted 5-bromo-5,6-dehydropiperidinones which react with L-SelectrideⓇ or methylcuprate to afford the saturated bromo-piperidinones with high diastereoselectivity. Condensation reactions of these products with thioamides afford thiazolopiperidines

ChemInform Abstract: Stereoselective Synthesis of Bromopiperidinones and Their Conversion to Annulated Heterocycles.

2010

N-Galactopyranosyland N-glucopyranosyl imines of aliphatic, aromatic and heteroaromatic aldehydes react with 1-methoxy-3-trimethylsilyloxy-1,3-butadiene in a domino Mannich-Michael reaction cascade to give 2-substituted 5,6-dehydro-piperidin-4-ones with high diastereoselectivity. Treatment of these cyclic enaminones with N-bromo-succinimide yields the corresponding 2-substituted 5-bromo-5,6-dehydropiperidinones which react with L-Selectride R © or methylcuprate to afford the saturated bromo-piperidinones with high diastereoselectivity. Condensation reactions of these products with thioamides afford thiazolopiperidines.

Toward an Understanding of Molecular Mechanism of Domino Cycloadditions. Density Functional Theory Study of the Reaction between Hexafluorobut-2-yne …

1998

Polyomino Number Theory (II)

2003

Polyominoes are connected plane figures formed of joining unit squares edge to edge. We have a monomino, a domino, two trominoes named I and V, five tetrominoes named I, L, N, O and T, respectively, and twelve pentominoes (a registered trademark of Solomon W. Golomb) named F, I, L, N, P, T, U, V, W, X, Y and Z respectively.

1,2,3-Triazole in Heterocyclic Compounds, Endowed with Biological Activity, through 1,3-Dipolar Cycloadditions

2014

1,3-Dipolar cycloaddition reactions can be considered a powerful synthetic tool in the building of heterocyclic rings, with applications in different fields. In this review we focus on the synthesis of biologically active compounds possessing the 1,2,3-triazole core through 1,3-dipolar cycloaddition reactions. The 1,2,3-triazole skeleton can be present as a single disubstituted ring, as a linker between two molecules, or embedded in a polyheterocycle. The cycloaddition reactions are usually catalysed by copper or ruthenium. Domino reactions can be achieved through dipolarophile anion formation, generally followed by cyclisation. The variety of attainable heterocyclic structures gives an ill…

The domino reaction between 4,6-dinitrobenzofuroxan and cyclopentadiene. Insights on the nature of the molecular mechanism

2004

Abstract The molecular mechanism of the domino reaction between 4,6-dinitrobenzofuroxan, 1 , and cyclopentadiene, Cp, to give the adduct 11 is examined through density functional theory (DFT) calculations at B3LYP/6-31G* level. This domino reaction comprises two consecutive formally [4+2] cycloadditions. The first one is a two-center addition initialized by the nucleophilic attack of Cp to the more electrophilic center of 1 . The subsequent cyclization can take place along two competitive channels associated to the formation of a second C–C bond yielding the formally [2+4] cycloadduct 9 , or a C–O bond yielding the formally [4+2] cycloadduct 10 . The second cycloaddition is a stepwise proce…