One–pot Reaction for the Convenient Synthesis of Functionalized 2‐Oxaspiro[bicyclo[2.2.1]heptane‐2,3′‐indolines]

Abstract

An efficient synthetic protocol for functionalized 2-oxaspiro [bicyclo[2.2.1]heptane-2,3'-indolines] was successfully developed by one-pot two-step reaction of phenacyl bromides, malononitrile and 3-methyleneoxindolines in ethanol in the presence of triethylamine. On the other hand, the similar threecomponent reaction of phenacyl bromides, ethyl cyanoacetate and 3-methyleneoxindolines afforded functionalized spiro[cyclopentane-1,3'-indoline] derivatives.

Chemoselective and one-pot synthesis of novel coumarin-based cyclopenta[c]pyrans via base-mediated reaction of α,β-unsaturated coumarins and β-ketodinitriles

“…The mechanism of the rst step including b-ketodinitriles formation is known. [32][33][34][35][36][37][38]…”

Selective synthesis of multifunctionalized cyclopent-3-ene-1-carboxamides and 2-oxabicyclo[2.2.1]heptane derivatives

“…To explain the formation of different cyclic compounds, a domino reaction mechanism was proposed as shown in Scheme 2 on the basis of previous work 5 and the present experiments. In the presence of a base, a carbanion ( A ) was in situ generated by deprotonation.…”

“…3,4 For example, Estevez and coworkers successfully found the intramolecular alkylation of methyl-5- O -benzyl-3,6-deoxy-6-nitro-α- d -glucofuranoside into the corresponding 2-oxabicyclo[2.2.1]heptane derivatives (eqn (1) in Scheme 1). 5 a Ramachary and coworkers found that the unique 5-oxaspiro[bicyclo[2.2.1]heptane-2,3′-indolin]-2′-ones can be obtained in excellent diastereoselectivity (dr > 99 : 1) by double reduction of olefin and carbonyl groups with NaBH 4 (eqn (2) in Scheme 1). 5 b In this respect, we successfully found that the base promoted domino reaction of malononitrile with two molecules of 3-phencylideneoxindoles resulted in novel 7-(2-oxoindolin-3-yl)-2-oxaspiro[bicyclo[2.2.1]heptane-6,3′-indolines] in various diastereoselectivities (eqn (3) in Scheme 1).…”

“…5 b In this respect, we successfully found that the base promoted domino reaction of malononitrile with two molecules of 3-phencylideneoxindoles resulted in novel 7-(2-oxoindolin-3-yl)-2-oxaspiro[bicyclo[2.2.1]heptane-6,3′-indolines] in various diastereoselectivities (eqn (3) in Scheme 1). 5 Very recently, we also developed efficient synthesis of functionalized 2-oxaspiro[bicyclo[2.2.1]heptane-2,3′-indolines] by a triethylamine mediated reaction of phenacylmalononitriles and 3-methyleneoxindolines in ethanol (eqn (4) in Scheme 1). 5 d Phenacylmalononitrile contains one carbonyl group, two cyano groups and an activated methylene unit, and therefore it exhibits versatile reactivity and has been widely employed in many synthetic reactions.…”

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

“…On the other hand, phenacylmalononitrile is also a readily available substrate, which can be easily prepared through a base-promoted substitution reaction of phenacyl bromide with malononitrile under mild conditions [11][12][13][14][15][16]. In many practical cases, phenacylmalononitriles could be conveniently generated in situ by directly using a mixture of phenacyl bromide and malononitrile in the reaction system [17][18][19][20][21][22]. As a consequence, the unique features of phenacylmalononitriles make them good candidates for the efficient construction of diverse carbocyclic and heterocyclic compounds [23][24][25][26][27][28][29][30].…”