Rapid access to diverse, trifluoromethyl-substituted alkenes using complementary strategies

Abstract

Herein describes two complementary methods, a one-step cross-coupling and the functionalization of a ‘masked’ functionality, to access diverse trifluoromethyl alkenes.

Redox-Neutral Photocatalytic Cyclopropanation via Radical/Polar Crossover

“…Trifluoromethyl-substituted alkenes 2 were initially selected for exploring the proposed cyclopropanation given their known compatibility with photoredox catalysis and proficiency as radical acceptors. , In addition, success here would allow the mild, one-step preparation of valuable TFCps 3 from trifluoromethyl-substituted alkenes. Given the ease with which these olefins can now easily be accessed from commercially available trifluoromethyl ketones, aryl halides, or organoboron reagents, success here would provide a regiospecific means to install the TFCp motif on virtually any scaffold (arene, hetereoarene, aliphatic, etc., Figure ).…”

Alkaline Earth Metal Template (Cross‐)Coupling Reactions with Hybrid Disila‐Crown Ether Analogues

“…From the perspective of Si−O bond activation, weakening of Si−O bonds is of considerable significance regarding the conversion of silicates to silanes. Especially dicatecholato‐silicate(IV) complexes are frequently used as precursors for either silane synthesis or functionalization of various organic molecules . Most recently, a collaborative research of Ollivier and co‐workers together with Fensterbank and co‐workers demonstrated a new synthesis for ketones, in this context employing acyl chlorides …”

“…Especially dicatecholato-silicate(IV) complexes are frequently used as precursors for either silane synthesis or functionalization of various organic molecules. [35][36][37][38][39][40][41][42][43] Most recently,acollaborative research of Ollivier and co-workerst ogether with Fensterbank and co-workers demonstrated an ew synthesis for ketones,i nt his context employinga cyl chlorides. [44]…”

N-Heterocyclic Carbene (NHC) Organocatalytic One-Pot Reaction for the Enantioselective Synthesis of Fluoromethylated Chromenones

“…As a part of our ongoing interest in carbene catalysis, we herein disclose a new strategy for the synthesis of enantiopure fluoromethyl-substituted chromenones via a one-pot carbene-catalyzed umpolung/oxidation process (Scheme ). After the formation of the Breslow intermediate I by the carbene catalyst with the aldehyde, the CF 3 - or CF 2 H-tethered moderately electron-poor double bond underwent an intramolecular proton transfer to give the hydroacylation intermediate II . The release of the carbene and oxidation of 3 finally delivered the chromenone containing a fluoromethyl-substituted stereogenic center.…”

“…Trisubstituted alkene 1a′ with the Z configuration ( E / Z < 5:95) was first subjected to the reaction conditions (Scheme , eq 3), the reaction delivered the product ( R )- 2a in high yield and ee, in contrast with the result of the model substrate 1a ( E / Z > 95:5) which afforded ( S )- 2a . This observation implied an intramolecular proton transfer from the OH group of the Breslow intermediate to the terminal carbon atom of the double bond during the reaction process . These assumptions are supported in part by the isolation of deuterated 4H-chromenone derivative 2a-D from the reaction mixture when deuterated 1a-D was used as the substrate under the same conditions (Scheme , eq 4).…”