The Baylis-Hillman reaction: An expedient synthesis of (Z)-keto allyl bromides and chlorides

The Baylis-Hillman Reaction: One-Pot Stereoselective Synthesis of Methyl (2E)-3-Aryl-2-hydroxymethylprop-2-enoates

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] In continuation of our interest in the development of the Baylis-Hillman reaction as a potential source for stereoselective processes, 9-14 we herein report simple, convenient and one-pot stereoselective transformation of methyl 3-aryl-3-hydroxy-2-methylenepropanoates, the Baylis-Hillman adducts obtained from the activated alkene, methyl acrylate, into methyl (2E)-3-aryl-2-hydroxymethylprop-2-enoates via the successive treatment with acetic anhydride/trimethylsilyl trifluoromethanesulfonate (TMSOTf), and potassium carbonate/methanol in very good yields.(2E)-2-Hydroxymethylalk-2-enoic acids and their esters are useful synthons for synthesis of various biologically active molecules. [15][16][17][18][19][20][21][22] However, there are only a few methods available in the literature for synthesis of these important molecules.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] In continuation of our interest in the development of the Baylis-Hillman reaction as a potential source for stereoselective processes, [9][10][11][12][13][14] we herein report simple, convenient and one-pot stereoselective transformation of methyl 3-aryl-3-hydroxy-2-methylenepropanoates, the Baylis-Hillman adducts obtained from the activated alkene, methyl acrylate, into methyl (2E)-3-aryl-2-hydroxymethylprop-2-enoates via the successive treatment with acetic anhydride/trimethylsilyl trifluoromethanesulfonate (TMSOTf), and potassium carbonate/methanol in very good yields.…”

Stereoselective Transformation of Baylis-Hillman Adducts into (3E)-3-(Alkoxymethyl)alk-3-en-2-ones

“…The (E)-configuration was assigned by the chemical shift value ( 1 H NMR) of the vinylic proton 26,27 in analogy with that of (3Z)-3-(halomethyl)alk-3-en-2-ones. 25 The (E)-configuration was further confirmed by a 2D NOESY experiment. The Baylis−Hillman adducts 1b-h under similar reaction conditions provided (3E)-3-(methoxymethyl)alk-3-en-2-ones 2b-h in good yields (Scheme, Table 1).…”

“…[19][20][21][22][23][24] Recently we have successfully transformed 4-hydroxy-3-methylenealkan-2-ones into (3Z)-3-(bromomethyl)alk-3-en-2-ones and (3Z)-3-(chloromethyl)alk-3-en-2-ones. 25 With a view to transform the Baylis−Hillman adducts 1, obtained from methyl vinyl ketone, into (3E)-3-(methoxymethyl)alk-3-en-2-ones, we first carried out the reaction between 4-hydroxy-3-methylene-4-phenylbutan-2one (1a) and methanol under various conditions. The best results were obtained when 1a was treated with excess methanol in the presence of p-toluenesulfonic acid at room temperature to provide after usual workup and column chromatography, pure (3E)-3-(methoxymethyl)-4phenylbut-3-en-2-one (2a) in 75% yield (Scheme).…”

Three-Component Halo Aldol Condensation of Thioacrylates with Aldehydes Mediated by Titanium (IV) Halide

“…The Baylis-Hillman-type C(sp 3 )-C(sp 2 ) single bond formation has become an active area in synthetic organic chemistry [ 1 , 3 ], but the direct carbon-carbon double formation under Baylis-Hillman-type conditions to give α-halomethyl vinyl carbonyl compounds have not been well documented. So far, the synthesis of α-halomethyl olefins has been achieved by treatment of Baylis-Hillman adducts with various halogenating reagents such as NBS/Me 2 S, hydrogen halides and CuBr 2 /SiO 2 [ 4 ]. Recently, we developed a new method for the synthesis of α-halomethyl vinyl ketones via a one-pot tandem difunctionalization of α,β-unsaturated ketones [ 5 , 6 ].…”