2-Tributylstannyl-2-propen-1-yl acetate (2), which can be easily prepared from ethyl propynoate (5), represents a useful precursor to a variety of 2-tributylstannyl-1-alkenes of general formula 1. Thus, treatment of 2 with complex organocopper species of general formula RCu.MgBrX.LiBr (4) (R = alkyl, aryl, benzyl, allyl) affords compounds 1 in fair to excellent yields. However, this procedure is unsuccessful for the preparation of 2-tributylstannyl-1,4-pentadiene (1e) and 2,3-bis(tributylstannyl)-1-propene (1g). Nevertheless, compound Ig contaminated by hexabutylditin (13) can be synthetized by palladium-catalyzed reaction between 2 and (tributylslannyl)diethylaluminum (15). The reactions of (E)-2-tributylstannyl-2-octen-1-yl acetate (22) with compounds 4h (R = i-Bu; X = Br) and 4b (R = Ph; X = Br) have been also investigated. These reactions, when carried out in THF solution, provide mixtures of two regioisomers of general formula 23 and 1, respectively, in which the prevailing components are those derived from a gamma-substitution reaction. Compound 23b, free of the corresponding regioisomer 1k, has been synthetized in low yield by palladium-catalyzed cross-coupling reaction between 22 and phenyltrimethylstannane (25). Moreover, two N-substituted derivatives of 3-amino-2-tributylstannyl-1-propene, i.e. compounds II and Im have been prepared by palladium-catalyzed amination of 2.
SYNTHESIS OF 2-TRIBUTYLSTANNYL-1-ALKENES FROM 2-TRIBUTYLSTANNYL-2-PROPEN-1-YL ACETATE
BELLINA, FABIO;CARPITA, ADRIANO;
1994-01-01
Abstract
2-Tributylstannyl-2-propen-1-yl acetate (2), which can be easily prepared from ethyl propynoate (5), represents a useful precursor to a variety of 2-tributylstannyl-1-alkenes of general formula 1. Thus, treatment of 2 with complex organocopper species of general formula RCu.MgBrX.LiBr (4) (R = alkyl, aryl, benzyl, allyl) affords compounds 1 in fair to excellent yields. However, this procedure is unsuccessful for the preparation of 2-tributylstannyl-1,4-pentadiene (1e) and 2,3-bis(tributylstannyl)-1-propene (1g). Nevertheless, compound Ig contaminated by hexabutylditin (13) can be synthetized by palladium-catalyzed reaction between 2 and (tributylslannyl)diethylaluminum (15). The reactions of (E)-2-tributylstannyl-2-octen-1-yl acetate (22) with compounds 4h (R = i-Bu; X = Br) and 4b (R = Ph; X = Br) have been also investigated. These reactions, when carried out in THF solution, provide mixtures of two regioisomers of general formula 23 and 1, respectively, in which the prevailing components are those derived from a gamma-substitution reaction. Compound 23b, free of the corresponding regioisomer 1k, has been synthetized in low yield by palladium-catalyzed cross-coupling reaction between 22 and phenyltrimethylstannane (25). Moreover, two N-substituted derivatives of 3-amino-2-tributylstannyl-1-propene, i.e. compounds II and Im have been prepared by palladium-catalyzed amination of 2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
