نتایج جستجو برای: cyclo ketalization

تعداد نتایج: 4572  

2014
Sambasivarao Kotha Nampalli Sreenivasachary Deepak Deodhar Mobin Shaikh

The title penta-cyclo-undecane cage derivative, C13H14OS2, was identified during a thio-ketalization reaction. The reaction selectively gave the title compound and the product corresponding to bis-ketal was not formed. The title compound exhibits unusual Csp (3)-Csp (3) single bond lengths ranging from 1.495 (3) to 1.581 (2) and strained bond angles as small as 89.29 (12) and as large as 115.11...

Journal: :Chemistry 2023

Second-generation biomass (BM) can be produced in amounts that meet worldwide fuel demands. However, BM favors parallel and undesirable reactions its transformation chain. We circumvent this problem by first modifying ketalization, giving a user-friendly liquid we named BP (bio-petroleum). This study converted representative compound of BP, DX (1,2:3,5-di-O-isopropylidene-α-D-xylofuranose), mix...

Journal: :Chemical communications 2005
Isamu Shiina Yo-ichi Kawakita Ryoutarou Ibuka Kazutoshi Yokoyama Yu-suke Yamai

An efficient method for the synthesis of (+)-buergerinin F is established via the enantioselective aldol reaction of a tetra-substituted ketene silyl acetal with crotonaldehyde, followed by intramolecular Wacker-type ketalization.

Journal: :Chemical communications 2011
Jayasree M Srinivasan Priya A Mathew Amie L Williams John C Huffman Jeffrey N Johnston

A concise synthesis of a highly functionalized intermediate lacking only C10 of the mitomycin backbone is described. The key to this development is the Brønsted acid-catalyzed aza-Darzens reaction used to forge the cis-aziridine. Additionally an oxidative ketalization fortuitously occurs during the quinone-enamine coupling step, leading to an orthogonally protected hydroquinone.

Journal: :Organic & biomolecular chemistry 2013
Yan Yang Meng Gao Wen-Ming Shu Liu-Ming Wu Dong-Xue Zhang An-Xin Wu

A highly efficient method for the direct synthesis of α-iodoketals from methyl ketones has been developed via sustainable integration of orthogonal tandem catalytic reactions: copper(II) oxide catalyzed iodination reaction and the subsequent excess or regenerated iodine catalyzed regioselective ketalization reaction.

Journal: :Chinese Chemical Letters 2022

An inexpensive Fe doped aluminoborate consisted of 18% in PKU-1 material that exhibits high selectivity 4-hydroxymethy-2,2-dimethyl-1,3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h−1), and recyclable ability the ketalization glycerol to Solketal with acetone at 318 K has been developed. Our study demonstrated structure (less agglomerated iron species vs. FeOx clusters) can be ...

Journal: :Analytical science advances 2021

Abstract Under different concentrations of the base potassium deuteroxide KOD, progress reactions, such as enolization, D‐substitution, isomerization, and conformational changes diketopiperazine cyclo(L‐Pro‐L‐Xxx) cyclo(D‐Pro‐L‐Xxx) (Xxx = Phe, Tyr) in D 2 O solution, was investigated by 1 H nuclear magnetic resonance (NMR). Cyclo(L‐Pro‐L‐Xxx) is mostly isomerized to whereas only slightly even ...

Journal: :Organic letters 2012
Raul Navarro Sarah E Reisman

Synthetic efforts toward the chlorinated aza-propellane alkaloid acutumine (1) are described. The key vicinal quaternary centers were constructed by a photochemical [2 + 2] cycloaddition reaction of a furanyl-tetrahydroindolone. Dihydroxylation of the [2 + 2] product enabled a tandem retro-aldol/intramolecular ketalization reaction, which revealed the aza-propellane core of 1 while generating a...

Journal: :Chemical & Pharmaceutical Bulletin 2021

The addition of an aqueous solution diketopiperazine cyclo(Pro-Xxx) (Xxx: amino acid residue) to (?)-epigallocatechin-3-O-gallate (EGCg) led precipitation the complex EGCg and cyclo(Pro-Xxx). molecular capture abilities using were evaluated by ratio amount included in precipitates with that total used. Stronger hydrophobicity side chain residue a higher ability. Furthermore, ability decreased w...

2008
Yow-Fu Tsai Jen-Ta Yang Jhy-Der Chen Chia-Her Lin

The title compound, C(13)H(24)O(7), is the product of the ketalization of methyl l-(+)-rhamnopyran-oside with 2,3-butane-dione. It crystallizes with two mol-ecules in the asymmetric unit, which are connected by O-H⋯O hydrogen bonds. The C-3,4 diequatorial hydroxy groups of the methyl l-(+)-rhamnopyran-oside were protected, leaving the C-2 hydroxy group free. The l-(+)-rhamnopyran-oside and 2',3...

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