“…36 When treated with trifluoromethanesulfonic anhydride, cyclopropenones were converted to bis(cyclopropenyliumyl) ether dication 49. 37 Both cations 48 and 49 react with nitrogen nucleophiles to give amino-or pyridyl-substituted cations 50 (65-95%) 38 and 51 (87%), 39 was formed (eq 23), the structure of which was determined by X-ray crystallography. 40 The BF 3 (OH)group is present in the middle of the symmetrically hydrogen-bonded cyclopropenone and hydroxycyclopropenylium cation moieties, and the structural parameters of the two cyclic C 3 units take values between those of cyclopropenone and the hydroxycyclopropenylium cation.…”
Section: Cyclopropenylium Cation With Oxygen Substituent(s)mentioning
confidence: 99%
“…Both cations 48 and 49 react with nitrogen nucleophiles to give amino- or pyridyl-substituted cations 50 (65−95%) and 51 (87%), respectively (eqs 21 and 22). …”
Section: Cyclopropenylium Cation With Oxygen Substituent(s)mentioning
“…36 When treated with trifluoromethanesulfonic anhydride, cyclopropenones were converted to bis(cyclopropenyliumyl) ether dication 49. 37 Both cations 48 and 49 react with nitrogen nucleophiles to give amino-or pyridyl-substituted cations 50 (65-95%) 38 and 51 (87%), 39 was formed (eq 23), the structure of which was determined by X-ray crystallography. 40 The BF 3 (OH)group is present in the middle of the symmetrically hydrogen-bonded cyclopropenone and hydroxycyclopropenylium cation moieties, and the structural parameters of the two cyclic C 3 units take values between those of cyclopropenone and the hydroxycyclopropenylium cation.…”
Section: Cyclopropenylium Cation With Oxygen Substituent(s)mentioning
confidence: 99%
“…Both cations 48 and 49 react with nitrogen nucleophiles to give amino- or pyridyl-substituted cations 50 (65−95%) and 51 (87%), respectively (eqs 21 and 22). …”
Section: Cyclopropenylium Cation With Oxygen Substituent(s)mentioning
“…35 Among the triafulvenes investigated in this paper (Scheme 2), the parent triafulvene T1b and several derivatives of T5 have previously been generated. [36][37][38][39][40] Fulvene T1b was estimated to have a half-life of 20 h in pentane at -78 °C, 36 while on the other hand, the T5 derivatives are relatively stable at ambient conditions. 39,40 As seen in Table 1, the degree of aromaticity according to HOMA varies widely among the selected triafulvenes; T3a is antiaromatic (a markedly negative HOMA), whereas T1c, T4c, and especially T5c have some aromatic character (positive HOMA).…”
Section: Resultsmentioning
confidence: 99%
“…[36][37][38][39][40] Fulvene T1b was estimated to have a half-life of 20 h in pentane at -78 °C, 36 while on the other hand, the T5 derivatives are relatively stable at ambient conditions. 39,40 As seen in Table 1, the degree of aromaticity according to HOMA varies widely among the selected triafulvenes; T3a is antiaromatic (a markedly negative HOMA), whereas T1c, T4c, and especially T5c have some aromatic character (positive HOMA). For T3 and T4 series where the ring substituent Y is an EWG and for T5 where the ring-substituent is an EDG, the aromaticity is significantly and steadily enhanced as the exocyclic substituent X increases in EWG character (Figure 3A).…”
The extent of substituent influence on the vertical electron affinities (EAs) and ionization energies (IEs) of 43 substituted tria-, penta-, and heptafulvenes was examined computationally at the OVGF/6-311G(d)//B3LYP/6-311G(d) level of theory and compared with those of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as representing strong electron-acceptor and -donor compounds, respectively. The substituents X at the exocyclic positions of the fulvenes were either NH(2), H, or CN, while the substituents Y at the ring positions were H, Cl, F, CN, or NH(2). The variations of the EAs and IEs were rationalized by qualitative arguments based on frontier orbital symmetries for the different fulvene classes with either X or Y being constant. The minimum and maximum values found for the calculated EAs of the tria-, penta-, and heptafulvenes were 0.51-2.05, 0.24-3.63, and 0.53-3.14 eV, respectively, and for the IEs 5.27-9.96, 7.07-10.31, and 6.35-10.59 eV, respectively. Two of the investigated fulvenes outperform TCNQ (calcd EA = 2.63 eV) and one outperforms TTF (calcd IE = 6.25 eV) with regard to acceptor and donor abilities, respectively. We also evaluated the properties of bis(fulvene)s, i.e., compounds composed of a donor-type heptafulvene fused with an acceptor-type pentafulvene, and it was revealed that these bis(fulvene)s can be designed so that the IE and EA of the two separate fulvene segments are retained, potentially allowing for the design of compact donor-acceptor dyads.
“…Our design of a cyclopropenone catalyzed alcohol inversion is shown in Scheme . In previous work by our group and others, it has been demonstrated that a cyclopropenone 1 can undergo conversion to a cyclopropenium salt ( 2 ) by the action of acid anhydrides including methanesulfonic anhydride (Ms 2 O). Alkylation of an alcohol substrate 3 by cyclopropenium ion, followed by reionization, leads to formation of the cyclopropenium activated intermediate 5 .…”
The cyclopropenone catalyzed nucleophilic substitution of alcohols by methanesulfonate ion with inversion of configuration is described. This work provides an alternative to the Mitsunobu reaction that avoids the use of azodicarboxylates and generation of hydrazine and phosphine oxide byproducts. This transformation is shown to be compatible with a range of functionality. A cyclopropenone scavenge strategy is demonstrated to aid purification.
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