Palladium–catalyzed synthesis of 2,3-dihydro-2-substituted-2-vinyl-1,4-benzodioxins

Abstract

Various 2,3-dihydro-2-substituted-2-vinyl-1,4-benzodioxins 6 are obtained by alkylation of the methyl carbonate of 2,3-dihydro-1,4-benzodioxin-2-ylideneethanol 5 with various carbon nucleophiles in the presence of a palladium complex. Altough the yields in alkytion products are good in the case of a non-bulky nucleophile, formation of the diene 7 was generally observed when a bulky nucleophile was used.

Perspectives on 1,4-Benzodioxins, 1,4-Benzoxazines and their 2,3-Dihydro Derivatives

“…2,3-Dihydro-2-aryl(alkyl)idene-1,4-benzodioxins X (Figure 11) constitute an integral part of the 1,4-benzodioxin and 1,4-benzodioxane family. Hydrogenation 50 of the external vinylic bond (at C-2) can afford the 1,4-benzodioxanes derivatives, while base-promoted 33 or metalcatalyzed methods 51 can afford 1,4-benzodioxin derivatives. Synthesis of this class of heterocycles using either classical methods or applying metal-catalyzed reactions is an emerging area of organic synthesis.…”

“…Later, Sinou 51 reported the synthesis of various 2-vinyl-1,4-benzodioxane derivatives 113 as shown in Scheme 30. Product 111 was obtained starting from catechol 35a and 110 under Pd 2 (dba) 3 -catalyzed reactions followed by desilylation.…”