Isoindoles with acetylenic esters

Dihydronaphthalen-1,4-iwmes from Isoindoles The naphthalen-l,4-imine derivatives 91-99 have been obtained by addition of acetylenedicarboxylic esters to the appropriate isoindoles. 3- ss Some such adducts react further with acetylenic esters (see Sections III, G and H), so that A -ethyl- and A-n-butylisoindole give 1 2 adducts with dimethyl aoetylenedicarboxylate instead. iV-Methylisoindole appears to be exceptional in giving an oily 2 1 adduct, for which structure (100) was suggested on analogy with the 2 1 adduct obtained from l,3-diphenylbenz[c]furan and acetylenedicarboxylic acid. ... 

Isoindoles such as 1,3-diphenyl-,1911,3,4,7-tetramethyl-, and 2-benzyl-1,3,4,7-tetramethylisoindole192 react with acetylenic esters across the... 

Dimethyl acetylenedicarboxylate and 1 -methylpyrrole combine yielding mainly the dihydroindole 6. This is readily explained by assuming that the adduct 5 is first formed and that it then combines with a second molecule of the ester as indicated.71 This reaction has already been reviewed,1 and, although attempts to isolate compound 5 have failed, a corresponding compound in the isoindole series192 has been obtained and gives the appropriate analog of 6 with more of the acetylenic ester. 

---