title: One-pot novel regioselective cycloisomerization synthesis of 2-substituted or 3-substituted 4H-furo[3,2-c]chromene through the intermediate cyclopropenes of 3-diazochroman-4-one and phenylacetylene.
abstract: A new class of cyclopropenes containing a chroman-4-one motif were synthesized using 3-diazochroman-4-one and phenylacetylene with rhodium(II) catalyst and followed by cycloisomerization to give 2-substituted or 3-substituted 4H-furo[3,2-c]chromene, respectively. Using BF3·Et2O as catalyst, 2-substituted 4H-furo[3,2-c]chromene was exclusively obtained in 70% yield. Using Cu(OTf)2 as catalyst, 3-substituted 4H-furo[3,2-c]chromene was obtained in 95% yield with 98:2 regioselectivity. A one-pot cascade addition-cycloisomerization process was also developed with no need to isolate cyclopropenes of chroman-4-one intermediates.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University , Lanzhou 730000, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Gong
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Zhao
authors.forename: Fuming
authors.initials: F
authors.lastname: Zhang
authors.forename: Songyun
authors.initials: S
authors.lastname: Wu
authors.forename: Guangqi
authors.initials: G
authors.lastname: Yan
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Quan
authors.forename: Baochun
authors.initials: B
authors.lastname: Ma