126918-29-4Relevant articles and documents
Synthesis and reactivity of α-sulfenyl-β-chloroenones, including oxidation and Stille cross-coupling to form chalcone derivatives
Kearney, Aoife M.,Murphy, Linda,Murphy, Chloe C.,Eccles, Kevin S.,Lawrence, Simon E.,Collins, Stuart G.,Maguire, Anita R.
supporting information, (2021/05/04)
The synthesis of a range of novel α-sulfenyl-β-chloroenones from the corresponding α-sulfenylketones, via a NCS mediated chlorination cascade, is described. The scope of the reaction has been investigated and compounds bearing alkyl- and arylthio substituents have been synthesised. In most instances, the Z α-sulfenyl-β-chloroenones were formed as the major products, while variation of the substituent at the β-carbon position led to an alteration in stereoselectivity. Stille cross-coupling with the Z α-sulfenyl-β-chloroenones led to selective formation of Z sulfenyl chalcones, while the E α-sulfenyl-β-chloroenones did not react under the same conditions. Oxidation of the Z α-sulfenyl-β-chloroenones was followed by isomerisation, leading to the E α-sulfinyl-β-chloroenones. Stille cross-coupling with the E α-sulfinyl-β-chloroenones produced the E sulfinyl chalcones. Either the E or Z sulfinyl chalcones can be obtained by altering the sequence of oxidation and Stille cross-coupling.
Stereoselective preparation of (E)-configured 1,2-disubstituted propenes from two aldehydes by a two-carbon stitching strategy: Convergent synthesis of 18,21-diisopropyl-geldanamycin hydroquinone and its C7 epimer
Hampel, Thomas,Neubauer, Thomas,Van Leeuwen, Thomas,Bach, Thorsten
supporting information; experimental part, p. 10382 - 10392 (2012/10/08)
The title compounds were synthesized in a longest sequence of 27 linear steps and with an overall yield of 2.9 and 3.9 %. In the course of the synthesis, two aldehydes representing carbon fragments C1-C7 (Eastern fragment) and C9-C21 (Western fragment) were prepared from D-mannitol, each of which incorporated a key stereogenic center at the respective secondary methyl ether group (C6, C12) from the chiral pool material. The assembly of the two aldehydes was achieved employing α-chloroethyl magnesium chloride as a two-carbon building block. The carbenoid reagent was generated from α-chloroethyl para-tolylsulfoxide by sulfoxide-magnesium exchange and it added smoothly to the highly sensitive aldehyde of the Eastern fragment (C1-C7). Upon oxidation, an α-chloroethyl ketone was generated, which underwent a clean and high-yielding reductive SmI2-promoted addition to the other aldehyde fragment. Dehydration delivered the key double bond between C8 and C9 in an overall yield of 72 % over four steps. The method was shown to be generally applicable to the racemization-free conversion of several aldehydes into the respective α-chloroethyl ketone (11 examples, 64-95 %) and to the coupling protocol (5 examples, 66-90 %). The further course of the geldanamycin hydroquinone synthesis included a diastereoselective reduction at C7 and the implementation of the amino group at C20. Since deprotection of the two isopropyl protecting groups could not be achieved in significant yields, the structure of 18,21-diisopropyl-geldanamycin hydroquinone was proven by its independent synthesis from the natural product. Convergency in the synthesis of the geldanamycin skeleton has been achieved by employing a magnesium carbenoid as a two-carbon building block, connecting two aldehyde fragments in an efficient and high yielding manner. The preparation of α-chloroethyl ketones from aldehydes has been investigated (11 examples, 64-95 % yield) and the title compounds have been prepared from advanced precursor 1. Copyright
Efficient α-chlorination of aryl ketones using aluminum chloride/urea-hydrogen peroxide in ionic liquid
Jong, Chan Lee,Hyun, Jung Park
, p. 777 - 780 (2007/10/03)
Effective α-chlorination reactions of aryl ketones into the corresponding α-chloroketones have been accomplished with aluminum chloride hexahydrate and urea-hydrogen peroxide in [bmim]BF4 ionic liquid. Copyright Taylor & Francis Group, LLC.
