Synthetic protocols, molecular polarity, and 13C NMR correlations for 1-aryl- and 1-diarylmethylidene-1H-cyclopropa[b]naphthalenes

Abstract

The Peterson olefination for alkylidenecycloproparene synthesis from a 1,1-disilylcycloproparene has been refined into five distinct protocols that have provided 43 new aryl- (5 and 6) and diaryl- (7 and 8), and aryl(phenyl)- (9 and 10) methylidene derivatives. The permanent dipole moments of these and other previously reported compounds have been measured and the direction of the dipole, to or from the cycloproparenyl moiety, established for each compound. The 13C NMR spectra are fully assigned and linear correlations of carbon chemical shift with the Hammett sigmap+ constants for each atom within the cycloproparene moiety are provided for the 8-11 compounds that comprise each substitution pattern present in 5-10.

Aryl-substituted methylidenecyclopropa[b]naphthalenes: synthesis and attempted silver(I)-mediated dimerization

“…19 The precise conditions needed for a given carbonyl compound and 4 1,2 have been the subject of detailed scrutiny, and fall into five distinct procedures that allow for the convenient synthesis of new derivatives. 3 While these procedures do not justify further discussion here, use of 'Method 1' has provided easy access to the previously known 1-phenyl- ; 43% ; 45%…”

“…1 and 2, [1][2][3] have continued to provide a source of fascination 4 since their discovery in 1984, 5 not least because the various derivatives have unexpected polarities, [6][7][8] fluorescence characteristics, 9 and unusual properties. 4,10,11 Recently, we described five protocols that allow for the synthesis of an extensive series of 1-aryl-and 1-diaryl-methylidene-1H-cyclopropa [b]naphthalenes, their polarities, and the linear dependence of their cycloproparenyl 13 C NMR chemical shifts upon the Hammett σ p + constant of the remote aryl substituent.…”

“…4,10,11 Recently, we described five protocols that allow for the synthesis of an extensive series of 1-aryl-and 1-diaryl-methylidene-1H-cyclopropa [b]naphthalenes, their polarities, and the linear dependence of their cycloproparenyl 13 C NMR chemical shifts upon the Hammett σ p + constant of the remote aryl substituent. 3 We also addressed conjugated and cross-conjugated cycloproparene derivatives containing cyclopentadiene and dithiole sub-units, 12 and others with simple π bonds that enhance polarity through extended conjugation. 13 Despite these advances there is no recorded attempt to utilize these exocyclic alkenes in what would be a simple and straightforward synthesis of quinodimethanes from ring opening and dimerization as occurs for the parent cycloproparenes.…”

The Fulvalenes

“…[182] Reaction of the 1-(trimethylsilyl)cycloproparenyl anion with suberone or benzo[d]cycloheptatriene leads to the arene-fused triaheptafulvalenes 136-138 (Scheme 27) by analogy to the synthesis of 95-97. The molecules are polar but the polarity is small and in the range 1.2-1.6 D. [150,151] Scheme 26.…”

“…The synthesis of these compounds employs Peterson olefination of a ketone using a silyl-substituted cycloproparenyl anion and derivatives Scheme 17. 95-97 are stabilised by the arene fusion. [150,151] The molecules are polar and the crystal structures of 95 and 96 have been determined. [152] Despite these various studies parent 4 has not yet been prepared.…”