A Simple, Two-Step, Site-Specific Preparation of Fluorinated Naphthalene and Phenanthrene Derivatives from Fluorobromo-Substituted Alkenes

Abstract

A facile two-step procedure for the site-specific preparation of fluorinated naphthalene and phenanthrene derivatives is described. The Sonogashira reaction of bromofluoro-substituted alkenes with terminal alkynes, followed by base-catalyzed cyclization in refluxing N-methyl-2-pyrrolidinone (NMP), affords the corresponding fluorinated naphthalene and phenanthrene derivatives in good yields.

Site-specific preparation of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes via base-catalyzed cyclization of enyne derivatives

“…Similar to the mechanism proposed in our previous reports [20][21][22][23], the reaction pathway is illustrated in Scheme 2. First, the base catalyzes the isomerization of the enyne to the allene intermediate, which undergoes 6p cycloaddition to form the two-ring system.…”

“…(2)). The reduced olefin can be readily separated after the cyclization process has been completed [21,32,33].…”

“…Barton and coworkers reported fluorination of benzofurans with trifluorofluorooxymethane (CF 3 OF) to give CF 3 O and F adducts [19]. Recently, we have developed a novel base-catalyzed cyclization to site-specifically prepare substituted naphthalenes and polycyclic aromatic hydrocarbons [20][21][22][23]. Herein, we wish to report the utilization of this base-catalyzed cyclization for the site-specific preparation of substituted heterocyclic compounds, such as benzo [b]furans and benzo[b]thiophenes.…”

1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles

“…1). 75,76,77 He has also extended this methodology to the synthesis of phenanthrenes by cycloaromatization of o-(alkynyl)biphenyls 77 (Scheme 13, eq. 2) and of benzo [b]furanes and benzo [b]thiophenes from 1-heteroaryl-1-en-3-ynes (Scheme 13, eq.…”

Synthesis of 2-Phenylated 1,1-difluoro-1,3-enynes via Alkynylation of β,β-Difluoro-α-phenylvinylstannane

“…[6][7][8] Of particular interests in 1,3-enynes are fluorine-containing conjugated enynes which would be important building blocks for the synthesis of fluorinated compounds having unique biological and physical properties. [9][10][11][12] Although various methods for the preparation of nonfluorinated 1,3-enynes have been well documented in the previous literature, 13 there are only limited reports on the synthesis of fluorinated 1,3-enynes and most of them covered the synthesis of 1,2-difluorinated [14][15] or monofluorinated 1,3-enynes. [16][17][18][19][20][21][22] Moreover, only three examples on the synthesis of 1,1-difluoro-1,3-enyne derivatives having high reactivity toward nucleophiles were reported.…”