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The First Benzo[1,2:4,5]dicyclobutenones and Their Tricarbonylchromium Complexes
Author(s) -
Abdelhamid Ismail Abdelshafy,
Habib Osama Mahmoud Ali,
Butenschön Holger
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100551
Subject(s) - chemistry , aryne , acetal , nucleophile , stereoselectivity , hydrolysis , medicinal chemistry , tricyclic , diketone , stereochemistry , organic chemistry , catalysis
Treatment of 1,4‐dibromo‐2,5‐dimethoxybenzene ( 6 ) with NaNH 2 followed by 1,1‐dimethoxyethene ( 7 ) afforded the bi‐ and tricyclic acetals such as 8 and 9 as the products of [2+2] cycloadditions of the intermediate arynes. After chromatographic separation and acetal hydrolysis the title compounds 15 and 16 were obtained in high yields as the first representatives of their class. Complexation of the acetals with Cr(CO) 6 gave the corresponding tricarbonylchromium complexes in excellent yields. Subsequent deacetalization afforded the diketone complexes 18 and rac ‐ 20 , which underwent stereoselective nucleophilic diadditions at –78 °C.