Results 121 to 130 of about 490 (165)

ChemInform Abstract: CYCLOCONTRACTION ‐ SPIROANNULATION: A STEREOSELECTIVE APPROACH TO SPIROCYCLES

Chemischer Informationsdienst, 1983
AbstractDie Umsetzung der Ketosulfone (I) mit der Al‐Spezies (II) führt durch Cyclisierung [‐ (III)] und Ringkontraktion/Isomerisierung zu den Spirocyclen (V).
B. M. TROST, B. R. ADAMS
openaire   +1 more source

ChemInform Abstract: ORGANOBISCUPRATES. A SINGLE‐STEP SPIROANNULATION METHOD

Chemischer Informationsdienst, 1977
AbstractAus den Lw‐Dilithiopolymethylenen (I) erhält man mit Cu(I)‐thiophenolat (II) die Komplexe (III), die mit Benzoylchlorid zu den Diketonen (Va) und (Vb) führen.
P. A. WENDER, S. L. ECK
openaire   +1 more source

Synergistic [4 + 1] Spiroannulation and Selective Ring-Opening Strategy toward γ-Spirolactams.

Organic Letters
A unique and propitious [4 + 1] spiroannulation of 2-aryl-4H-benzo[d][1,3]oxazine with maleimide has been delineated, furnishing diversely embellished γ-spirolactams featuring pendant benzyl alcohol via Rh(III)-catalyzed consecutive ring closing/ring ...
Imtiaj Mondal, Koushik Naskar, Shantonu Roy, A. Purkait, Indubhusan Deb   +4 more
semanticscholar   +1 more source

ChemInform Abstract: α‐SUBSTITUTION‐SPIROANNULATION OF SATURATED KETONES

Chemischer Informationsdienst, 1984
AbstractDas mit Cyclopentanon als Ausgangsketon dargestellte Trimethylsilyloxy‐cyclopropan (I) lagert sich in Gegenwart des Brom‐Dioxan‐Komplexes in das Bromspiroketon (II) um, das bei der Oxidation mit MCPBA das Bromlacton (III) gibt.
B. M. TROST, M. K.‐T. MAO
openaire   +1 more source

C-H activation-initiated spiroannulation reactions and their applications in the synthesis of spirocyclic compounds.

Organic and biomolecular chemistry
Spirocyclic skeletons are prevalent in natural products, pharmaceuticals and organic functional materials. Meanwhile, transition-metal-catalyzed C-H activation reactions have demonstrated unparalleled advantages such as high efficiency, excellent atom ...
Qianting Zhou, Bin Li, Xinying Zhang, Xuesen Fan   +3 more
semanticscholar   +1 more source

Synthesis of γ-Spirolactams via Rh(III)-Catalyzed C-H Activation/Directing Group Migration/Dearomatization/Spiroannulation of Indoles with 1,3-Enynes.

Organic Letters
1,3-Enynes are valuable coupling partners in transition-metal-catalyzed C-H functionalizations. Certainly, aliphatic-substituted 1,3-enynes have been thoroughly investigated in C-H functionalizations, whereas aromatic-substituted 1,3-enynes remain ...
Sanjeev Kumar, Vinaykumar Kanchupalli
semanticscholar   +1 more source

Rh(III)-catalyzed sequential spiroannulation/lactonization of 3-aryl N sulfonyl ketimines with 4 hydroxy-2-alkynoates by C–H bond activation

New Journal of Chemistry
A sequential Rhodium(III)-catalyzed spiroannulation and lactonization strategy has been developed for the synthesis of a highly rigid spirobenzosultam lactones in good yields with high regioselectivity by means of aromatic ortho-C-H...
P. S., Ajay Chidrawar, K. Nagesh, S. Balasubramanian, Venkata Subba Reddy Basireddy   +4 more
semanticscholar   +1 more source

Rh(III)-Catalyzed Diastereodivergent Spiroannulation of Cyclic Imines with Activated Alkenes

Organic Letters, 2017
Rh(III)-catalyzed [3 + 2] annulation of cyclic N-sulfonyl or N-acyl ketimines with activated alkenes has been realized, leading to the synthesis of spirocycles with three continuous stereogenic centers. This atom-economic reaction proceeded efficiently under mild and redox-neutral conditions via a C-H activation pathway, and the coupling is ...
Bingxian Liu, Panjie Hu, Ying Zhang, Yunyun Li, Dachang Bai, Xingwei Li   +5 more
openaire   +2 more sources

Electrochemical Oxidation Enables Radical Dearomative Spiroannulation to 2H-Spiro[benzofuran-3,9'-fluoren]-2-one.

Chemistry
Developing pragmatic strategies for accessing functional benzofuran-2-ones from 3-([1,1'-biphenyl]-2-yl)benzofuran remains an enduring challenge. Herein, we have achieved a highly discriminating electrochemical oxidative dearomative spiroannulation of 3-(
Yuanyuan Yue, Xiaohui Guo, Jianhang Zhang, Zhiqiang Zhang, Yilin Zhang, Qinghu Tang, Ruopeng Bai, Hong Yi, Jianming Liu   +8 more
semanticscholar   +1 more source

DFT Investigation on Palladium-Catalyzed [2 + 2 + 1] Spiroannulation between Aryl Halides and Alkynes: Mechanism, Base Additive Role, and Solvent and Ligand Effects.

Journal of Physical Chemistry A
Transition metal-catalyzed spiroannulations are practical strategies for constructing spirocyclic skeletons of pharmaceutical and biological significance, yet the microscopic mechanism still lacks in-depth explorations. Here, the palladium-catalyzed [2 +
Xue Tan, Wen-Ji Bai, Yu-Bing Shi, Liangfei Duan, Weihua Mu   +4 more
semanticscholar   +1 more source