Organoboranes. 35. Reaction of alkylthioboronic esters with trichloromethyllithium: preparation of one-carbon-extended carboxylic acids and thioacetals from alkenes via hydroboration
An α‐Cyclopropanation of Carbonyl Derivatives by Oxidative Umpolung
作者:Adriano Bauer、Giovanni Di Mauro、Jing Li、Nuno Maulide
DOI:10.1002/anie.202007439
日期:2020.10.5
nucleophiles is often associated with umpolung and cationic mechanisms. Herein, we report a general process converting a range of ketone derivatives into α‐cyclopropanated ketones by oxidative umpolung. Mechanistic investigation and careful characterization of side products revealed that the reaction follows an unexpected pathway and suggests the intermediacy of non‐classical carbocations.
A New Synthetic Application of 1,2-Benzodithiolium Cations: Synthesis of Aldehydes by 1-Carbon Homologation of Carbonyl Compounds
作者:Maurizio Ceruti、Iacopo Degani、Rita Fochi
DOI:10.1055/s-1987-27857
日期:——
Eleven aldehydes (6a-1) were synthesized by 1-carbon homologation of ketones and aldehydes according to the following sequence: Horner-Emmons reaction of 2-(O,O-dimethylphosphonyl)-1,3-benzodithiole (1)and various carbonyl compounds (2) to give benzo-1,4-dithiafulvenes (3); reduction with sodium borohydride and tetrafluoroboric acid-ether complex in dry acetonitrile to 1,3-benzodithioles (5); subsequent hydrolysis of these with mercury(II)oxide and aqueous tetrafluoroboric acid (35%) in tetrahydrofuran. The procedure is simple, of wide application, and afforded pure aldehydes in good overall yields (55-88%).
Highly Regioselective Hydroformylation with Hemispherical Chelators
作者:David Sémeril、Dominique Matt、Loïc Toupet
DOI:10.1002/chem.200800747
日期:2008.8.18
straightforwardly provide chelate complexes in which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C(2) axis and the two apically situated R groups. Hydroformylation of octene with the L(Pr)/Rh system turned out to be highly regioselective, the linear-to-branched (l:b) aldehyde ratio reaching 58:1. The l:b ratio significantly increased when the propyl groups were replaced
Organoboranes. 32. Homologation of alkylboronic esters with methoxy(phenylthio)methyllithium: regio- and stereocontrolled aldehyde synthesis from olefins via hydroboration
作者:Herbert C. Brown、Toshiro Imai
DOI:10.1021/ja00358a017
日期:1983.9
L'homologation d'alkyl-2 dioxaborinannes-1,3,2(I) en derives α-methoxyalkyl-2 (II) est realisee par reaction avec LiCH(OCH 3 )SC 6 H 5 suivie d'un traitement par HgCl 2 . Les intermediaires (II) sont oxydees par H 2 O 2 en tampon phosphate pour donner les aldehydes correspondants. Les groupes alkyles de (I) sont introduits par borhydratation
L'homologation d'alkyl-2 dioxaborinannes-1,3,2(I) en衍生α-甲氧基烷基-2 (II) est realisee par反应avec LiCH(OCH 3 )SC 6 H 5 suvie d'un traitement par HgCl 2 . Les intermediaires (II) sont oxydees par H 2 O 2 en tampon phosphate pour donner les aldehydes 通讯员。Les groupesalkales de (I) sont 介绍了par borhydration
Efficient Platinum(II) Catalyzed Hydroformylation Reaction in Water: Unusual Product Distribution in Micellar Media
Aldehydes are obtained with linear to branched ratios up to >99:1. With styrene derivatives also the corresponding benzaldehydes are formed. The catalyst can be separated by extraction of the organic products with hexane and recycled for at least four times with only a modest loss of activity and no effect on selectivity.