Nucleophilic Substitution Reactions at Chloro-Substituted Ozonides and at a Chlorinated Dimeric Peroxide
摘要:
Reactions of substituted 3-chloro-(2a-4a) and 3,5-dichloro-1,2,4-trioxolanes (9a, 10a) with AgBF4 in the presence of LiF gave the corresponding fluoro-substituted ozonides (2b-4b and 9b and 10b). Substitutions af some of these chlorinated ozonides by the methoxy and by the acetoxy groups, and of 3,6-dichloro-3,6-dimethyl-1,2,4,5-tetrox (22a) with the acetoxy group have been achieved, too.
Reactions of potassium fluoride in glacial acetic acid with chlorocarboxylic acids, amides, and chlorides. The effect of very strong hydrogen bonding on the nucleophilicity of the fluoride anion
作者:James H. Clark、John Emsley
DOI:10.1039/dt9750002129
日期:——
Although KF is very soluble in glacial aceticacid, the nucleophilicity of the fluoride ion therein is much reduced by the verystronghydrogen bonding which occurs between it and the solvent. The fluoride is in effect enhancing the nucleophilicity of the hydroxyl oxygen atom of the carboxylicacid group. Reaction of chlorocarboxylic acids and their derivatives with this reagent produces acetoxy- instead
作者:Ayan Maity、Robert J. Stanek、Bryce L. Anderson、Matthias Zeller、Allen D. Hunter、Curtis E. Moore、Arnold L. Rheingold、Thomas G. Gray
DOI:10.1021/om5009555
日期:2015.1.12
were determined for one bridging and one terminal fluoridecomplex. The terminal fluoride shows intramolecular hydrogen bonding to an adjacent 3,5-dimethylpyrazole ligand; a lesser interaction may occur between F and a nearby aromatic C–H bond. Terminal fluoridecomplexes react with carbon-, silicon-, and sulfur-based electrophiles. The new complexes phosphoresce with microsecond lifetimes at 77 and
Auxiliary controlled enantioselective synthesis of 3-aryl-prolines
作者:Stephan Laabs、Winfried Münch、Jan W Bats、Udo Nubbemeyer
DOI:10.1016/s0040-4020(01)01233-9
日期:2002.2
synthesis of opticallyactive cis 3-aryl proline derivatives was achieved in a five-step sequence involving an enantioselective aza-Claisen rearrangement as the key step. Initially, suitable cinnamyl amines were generated via a Pd(0) catalyzed amination of the corresponding N-allyl mesylates using opticallyactive proline derivatives as chiral auxiliaries. The zwitterionic aza-Claisen rearrangement with azidoacetyl
The flexible synthesis of defined substituted optically active indolizidinones starting from chiral pool (S)-proline and trans 4-hydroxy-(S)-proline is described. Several defined 2-vinylpyrrolidines were generated in short sequences. The aza-Claisen rearrangement using chloro and phenylketene equivalents delivered nine-membered-ring lactams with up to three stereogenic centres and pS-arranged E olefins
The bicyclic core of the pumiliotoxins was synthesized in nine to eleven steps starting from L-(−)-proline. This chiral pool starting material was initially converted into an optically active 2-vinylpyrrolidine by standard operations. The first key step allowed the generation of a nine-membered ring lactam by means of a zwitterionic aza-Claisen rearrangement. The 1,4 chirality transfer was found to