Diels−Alder Reactions of Perfluorobicyclo[2.2.0]hex-1(4)-ene with Aromatics

Abstract

[reaction: see text] The title perfluoroalkene cycloadds to a variety of aromatic hydrocarbons, including benzene. It is the first alkene to yield a Diels-Alder adduct with benzene and is thus among the most potent dienophiles known.

Novel polycyclic Diels-Alder adducts from ring distorted 3-aza[5] and 3-aza[6] (1,7) naphthalenophanes

“…Reaction of the 3-aza [5](1,7)naphthalenophane (1a) and 3-aza [6](1,7)naphthalenophanes (1b) and (1d) with tetracyanoethylene also proceeded smoothly under mild conditions, giving the 1:1 adducts (3a), (3b) and (3c) respectively in high yields (Scheme 2 and Structural assignments of the adducts (3a-c) were supported by spectroscopic and analytical data. The molecular formula of the adducts 3a and 3c were determined from high-resolution mass spectrometry and, in each case, were reinforced by elemental analysis.…”

“…The numbers on structure 2 refer to compounds with n = 2. In the case of the shorter bridged 3-aza [5](1,7)naphthalenophane (1a), the 1:1 adduct (2a) was obtained in 82% yield after a shorter period of time (completed reaction), indicating that (1a) is considerably more reactive than the larger bridged naphthalenophanes (1b) and (1c). This can be explained in terms of its higher strain 7,9 in comparison to that of (1b) and (1c).…”

“…The required 3-aza- [5] and [6]-(1,7)naphthalenophane precursors (1a, b, c) were prepared by application of the previously described 7,8 ring destruction methodology to the appropriate fused isoquinoline derivatives and reaction with cyanogen bromide or methyl chloroformate. Reduction of the carbamate 1d with lithium aluminium hydride then afforded 8 the naphthalenophane (1c).…”

“…The 3-aza [5](1,7)naphthalenophane 1a showed facile and selective dienophilic reactivity in the Diels-Alder reaction with electron deficient dienophiles. The 3-aza [6](1,7)naphthalenophanes 1b-d reacted similarly but were not as diene-like consistent with less naphthalene ring distortion with the longer bridging chain.…”

“…[1][2][3][4][5] If the planarity of the naphthalene is partially disrupted by bulky substituents or by incorporating the naphthalene moiety in a short-bridged cyclophane, then the feasibility of this reaction is likely to be increased. 6 Such a ring distortion occurs in the [5]-or [6]-aza-1,7-naphthalenophane systems. Diels-Alder reactions of these systems were of interest mechanistically to assess the effects of ring strain on reactivity.…”