14949-49-6Relevant articles and documents
Titanocene(II)-promoted cyclization of unsaturated thioacetals
Fujiwara, Tooru,Takeda, Takeshi
, p. 354 - 356 (1999)
The low-valent titanium species-promoted transformation of unsaturated thioacetals to cyclic compounds was studied. The cyclization of thioacetals having an olefin moiety proceeded with the loss of terminal olefin carbon to produce the corresponding five-
Light Harvesting for Rapid and Selective Reactions: Click Chemistry with Strain-Loadable Alkenes
Singh, Kamaljeet,Fennell, Christopher J.,Coutsias, Evangelos A.,Latifi, Reza,Hartson, Steve,Weaver, Jimmie D.
supporting information, p. 124 - 137 (2018/01/17)
Intramolecular strain is a powerful driving force for rapid and selective chemical reactions, and it is the cornerstone of strain-induced bioconjugation. However, the use of molecules with built-in strain is often complicated as a result of instability or selectivity issues. Here, we show that such strain, and subsequent cycloadditions, can be mediated by visible light via the harvesting of photochemical energy. Through theoretical investigations and molecular engineering of strain-loadable cycloalkenes, we demonstrate the rapid chemoselective cycloaddition of alkyl azides with unstrained cycloalkenes via the transiently (reversibly) formed trans-cycloalkene. We assess this system via the rapid bioconjugation of azide-functionalized insulin. An attractive feature of this process is the cleavable nature of the linker, which makes a catch-and-release strategy possible. In broader terms, we show that conversion of photochemical energy to intramolecular ring strain is a powerful strategy that can facilitate complex chemical transformations, even in biomolecular systems. Probing, isolating, and/or manipulating biologically relevant macromolecules is central to the study of their function in living systems. However, the synthetic tools available for performing the chemistry necessary for such studies are often difficult to use or limited in utility. In the approach presented here, light is converted to molecular strain energy, which can in turn be used for performing rapid and highly selective chemistry on macromolecular systems. Because it involves chemically stable and chemoselective reactions, this research not only opens up new possibilities for biomolecular functionalization and manipulation but also promises to make such experiments accessible to a broader class of researchers. The central concept of strain-loadable alkenes is general and provides a firm foundation for light-activated chemistry in complex environments. Strain-loadable alkenes are cycloalkenes that, when irradiated in the presence of a visible-light-absorbing photocatalyst, undergo double-bond isomerization. Because of engineered geometrical constraints, this isomerization results in significant molecular strain. Weaver and colleagues exploit this strain to dramatically accelerate the cycloaddition with azides, which are otherwise unreactive, in mixed molecular environments.
Role of the gem-difluoro moiety in the tandem ring-closing metathesis-olefin isomerization: Regioselective preparation of unsaturated lactams
Fustero, Santos,Sanchez-Rosello, Maria,Jimenez, Diego,Sanz-Cervera, Juan F.,Del Pozo, Carlos,Acena, Jose Luis
, p. 2706 - 2714 (2007/10/03)
Careful selection of the metathesis catalyst, solvent, and reaction conditions allows for the efficient and regioselective synthesis of isomeric fluorinated and nonfluorinated lactam derivatives II and III from precursor amides I through a ring-closing me
Ring-closing metathesis of titanium - Carbene complexes prepared from thioacetals having a carbon - Carbon double bond
Fujiwara, Tooru,Kato, Yoshiko,Takeda, Takeshi
, p. 4859 - 4869 (2007/10/03)
The ring-closing metathesis proceeded to give cycloalkenes in good yields when diphenyl thioacetals having a carbon-carbon double bond were treated with the low-valent titanium species Cp2Ti[P(OEt)3]2 in THF at room temperature and then at reflux. This methodology is successfully applied to the preparation of cyclic ethers and sulfides. (C) 2000 Published by Elsevier Science Ltd.
2,3,4,5-tetrahydro-1-benzoxepins, the use thereof and pharmaceutical products based on these compounds
-
, (2008/06/13)
2,3,4,5-Tetrahydro-1-benzoxepins of the formula I STR1 with R1 equaling, inter alia, H, alkyl, alkoxy, Hal, alkylsulfonyl, arylsulfonyl, R2 equaling H, alkyl, alkoxy, OH, R3 to R6 H or alkyl and X equaling STR2 have excellent efficacy as antihypertensives, as coronary therapeutics, as agents for the treatment of cardiac insufficiency, of disturbances of cerebral and peripheral blood flow or of disturbances of intestinal motility, premature labor, obstructions of the airways or of the urinary tract or of the biliary tract or as spasmolytics.
Conformational analysis of 3-substituted-2,3,4,5-tetrahydro-1-benzoxepin by 1H and 13C nuclear magnetic resonance
Lachapelle, A.,St-Jacques, M.
, p. 2575 - 2594 (2007/10/02)
2,3,4,5-Tetrahydro-1-benzoxepin (8) and its 3-substituted derivatives (9-13) have been studied by 1H and 13C dynamic nuclear magnetic resonance in a few solvent systems.The results show that, while 8 and its methyl derivative 9 exist solely in chair forms (C for 8 and Ce:Ca (96:4) for 9), the twist-boat (TB) conformation contributes significantly to the conformational equilibra of the derivatives 3-methoxy 10 (Ca:Ce:TB, 70:20:10), 3,3-dimethyl 11 (C:TB, 90:10), 3,3-methylmethoxy 12 (Ca:Ce:TB, 89:4:7), and 3,3-dimethoxy 13 (C:TB, 92:8).The analysis of several factors (steric, electrostatic, and electronic) on the conformational behaviour of these molecules shows why the TB form is a viable conformational alternative to destabilized chair forms in this benzoxepin system.
