98815-47-5Relevant articles and documents
Taking advantage of lithium monohalocarbenoid intrinsic α-elimination in 2-MeTHF: controlled epoxide ring-openingen routeto halohydrins
Ielo, Laura,Miele, Margherita,Pillari, Veronica,Senatore, Raffaele,Mirabile, Salvatore,Gitto, Rosaria,Holzer, Wolfgang,Alcántara, Andrés R.,Pace, Vittorio
supporting information, p. 2038 - 2043 (2021/03/16)
The intrinsic degradative α-elimination of Li carbenoids somehow complicates their use in synthesis as C1-synthons. Nevertheless, we herein report how boosting such an α-elimination is a straightforward strategy for accomplishing controlled ring-opening of epoxides to furnish the corresponding β-halohydrins. Crucial for the development of the method is the use of the eco-friendly solvent 2-MeTHF, which forces the degradation of the incipient monohalolithium, due to the very limited stabilizing effect of this solvent on the chemical integrity of the carbenoid. With this approach, high yields of the targeted compounds are consistently obtained under very high regiocontrol and, despite the basic nature of the reagents, no racemization of enantiopure materials is observed.
Reactions of 4-Substituted-2'-Halogenoacetophenones with Grignard Reagents
Crombie, Leslie,Hardy, Robert,Knight, David W.
, p. 1373 - 1380 (2007/10/02)
The initial reaction of 4-substituted 2'-halogenoacetophenones with an excess of methyl Grignard reagent is shown to be an attack at the 1'-carbonyl to form a halohydrin salt.The various reactions which then follow are substituent dependent.In the 4-hydroxy case the only product is 1-(4-hydroxyphenyl)-2-methylpropan-2-ol (13) which arises via a -aryl shift with simultaneous elimination of magnesium halide.When the substituent is 4-methoxy, a second pathway becomes important involving epoxide formation and a subsequent -hydride migration to the benzylic position, or attack of the Grignard reagent at the benzylic carbon of the epoxide.When the substituent is 4-bromo, the reaction proceeds exclusively via the epoxide and, following a -hydride shift, leads to the isomeric butanols (33) and (34).The reasons underlying such diversity of reactivity are discussed.
