烯胺合成

乙炔酯對環(huán)烯胺進(jìn)行環(huán)加成，接著重排擴(kuò)環(huán)，得到多兩個(gè)碳的環(huán)二烯胺的反應(yīng)。產(chǎn)物水解后可以得到多兩個(gè)碳的環(huán)二烯酮。

反應(yīng)機(jī)理

反應(yīng)操作

1-(N-Morpholino)-2,3-dicarbomethoxy-1,3-cycloheptadiene (4). DMAD 1 (16.2 g, 77.4 mmol) was added to morpholinocyclopentene 2 (11 g, 77.4 mmol) in PhH (40 mL) under N2 with ice cooling and stirring at such a rate that the temp never rose above 50 C. After a short supplementary stirring, the mixture was heated to reflux for 12 h. The solution was treated with excess of Et2O under cooling and the precipitate was filtered off. Recrystallization from Me2CO afforded 11.4 g of 4 in 48% yield, mp 167–168 C.

2,3-Dicarbomethoxy-3-cycloheptenone (5). A solution of 4 (1 g, 3.25 mmol) in MeOH (5 mL) and 32% HCl (1 mL) was heated to reflux. Water (2 mL) was added and the mixture was heated for another 10 min to reflux. After cooling, the precipitate was crystallized from MeOH:H2O 2:1 to give 610.5 mg of 5 in 90% yield, mp 63.5–64 C.

【Berchtold GA, J Org Chem, 1963, 28, 1459】

1 Brannock KC J Org Chem 1961 26 625

2 Berchtold GA J Org Chem 1961 26 3043

3 Berchtold GA J Org Chem 1963 28 1459

4 Hickmott PW Tetrahedron 1982 38 3363

5 Mark J Tetrahedron 2000 56 4317

6 Miesch M J Org Chem 2003 68 433

編譯自：Organic Syntheses Based On Name Reactions, 3RdEd, A. Hassner, Page 41.