Photoinduced Double Addition of Acetylene to 3-Oxocyclopent-1-ene-1-carbonitrile or 3-oxocyclopent-1-enyl acetate leading to 2,3-dihydro-1H-inden-1-one and other rearranged products
✍ Scribed by Marino Cavazza; Graziano Guella; Francesco Pietra
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- German
- Weight
- 405 KB
- Volume
- 71
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
UV Irradiation of 3-oxocyclopent-1-enyl acetate (17) and acetylene in MeCN at 0" gives, besides the product of normal enone-alkyne [2 + 21 cycloaddition (cis-4-oxobicyclo[3.2.0]hept-6-en-l-yl acetate, 18) and its product of oxd-di-n methane rearrangement (5-oxotricyclo[4.1 .0.02.']hept-2-yl acetate, 19), unexpected products of further addition of a molar equivalent of acetylene. These are indanone ( = 2,3-dihydro-lH-inden-l-one, 16), in 21 % yield, cis-l-cisoid-1,2-cis-2-(20) and cis-l-transoid-1,2-cis-2-7-oxotricyclo[4.3.O.Oz~s]non-3-en-l-yl acetate (21), 4-0x0-7-'exo'-vinyltricycl0[3.2.0.O~~~]hept-2-yl acetate (22), cis-4-0x0-6-'endo'-(23) and cis-4-0x0-6-'exo '-vinylbicyclo[3.2.0]hept-1-yl acetate (24), and cis-4-oxo-7-'exo'-vinylbicyclo[3.2.0]hept-l-y1 acetate (25). At least in part, indanone must be formed via intermediates 20 and 21. In fact, on heating a 9: 1 mixture 20/21, indanone is obtained quantitatively. With 3-oxocyclopent-1-ene-I-carbonitrile (15) in place of 17, indanone is formed in lower (8 %) yield besides much tars.