Incorporation of an allene unit into alpha-pinene: Generation of the cyclic allene 2,7,7-trimethylbicyclo[4.1.]octa-2,3-diene and its dimerization

Azizoglu, A
Ozen, R
Hokelek, T
Balcı, Metin
The reaction of etheral methyllithium with 3,3-dibromo-2,7,7-trimethyl-tricyclo[,4)] octane (2) was investigated. The generated carbene 12 undergoes intramolecular C-H insertion to provide the tetracyclic hydrocarbon 3 and the bicyclic allene 15, which undergoes [2 + 2] cyclodimerization. The structures of the formed allene dimers 16, 17, and 18 were elucidated by spectral means. The activation barriers for all possible C-H insertion products 3, 13, and 14 and the allene 15 were investigated by using density functional theory computations at the B3LYP/6-31G(d) level. It was found that the activation barriers for the formation of 3 and 15 (6.2 and 6.3 kcal mol(-1)) are much lower than that for the insertion products 13 and 14 (17.5 and 12.6 kcal mol(-1)), respectively. This prediction was completely in agreement with our experimental results.


Addition of trifluoromethyltrimethylsilane to acyl phosphonates: Synthesis of TMS-Protected 1-alkyl-1-trifluoromethyl-1-hydroxyphosphonates and 1-aryldifluoroethenyl phosphates
Demir, Ayhan Sıtkı; Eymur, Serkan (American Chemical Society (ACS), 2007-10-26)
Addition reactions of nucleophilic CF3TMS to acyl phosphonates were investigated. Various acyl phosphonates reacted readily with CF3TMS in the presence of K2CO3 in DMF at rt to give 1-alkyl-2,2,2-trifluoro-1-trimethylsilyloxyethylphosphonate in 70−90% yields. When benzoyl phosphonates were used as starting material, after addition of CF3, the formed alcoholate undergoes phosphonate−phosphate rearrangement to form the acyl anion, followed by elimination of F- to give 1-aryldifluoroethenyl phosphates in 87−97...
Substituent Effects on the Ring-Opening Mechanism of Lithium Bromocyclopropylidenoids to Allenes
AZİZOĞLU, AKIN; Balcı, Metin; Mieusset, Jean-Luc; Brinker, Udo H. (American Chemical Society (ACS), 2008-11-07)
The ring-opening reactions of lithium bromocyclopropylidenoids to allenes have been investigated computationally at the B3LYP/6-31 G(d) level of theory. Formally, two pathways can be considered: the reaction may either proceed in a concerted fashion or stepwise with the intermediacy of a free cyclopropylidene. In both cases, the loss of the bromide ion determines the kinetic of the reaction. The stability of the reactive intermediate, i.e., the carbene, is dependent on the substituent. Cyclopropylidenes bea...
Oxidation of Primary Alcohols to Aldehydes with N-Halamine-Containing Polymers
Akdağ, Akın; Öztürk, Perihan (Georg Thieme Verlag KG, 2013-11-12)
Polymeric N-halamines have been previously employed for organic reactions such as sulfide oxidation. In the present study, we employed polymeric N-halamines to oxidize primary alcohols selectively to the corresponding aldehydes in excellent yields. After reaction, the polymers can be recycled and then reused for the next reaction process.
Synthesis of 1,2,3,5- tetrasubstituted pyrrole derivatives via 5-exo-dig type cyclization and stereoselective functionalisation of ferrocene derivatives
Kayalar, Metin; Demir, Ayhan Sıtkı; Department of Chemistry (2005)
A convenient and new method for the synthesis of 1,2,3,5-tetrasubstituted pyrrole derivatives starting from 1,3,-dicarbonyl compounds through acid catalyzed cyclization reaction is described. Alkylation of 1,3-dicarbonyl compound with propargyl bromide followed by one step cyclization with the introduction of primary amines in the presence of catalytic amount of triflouroacetic acid (TFA) affords the corresponding pyrrole derivatives in high yields. The investigations on the studies of developing a new meth...
Transition structures, energetics, and nucleus-independent chemical shifts for divinylcyclobutene-to-cyclooctatriene rearrangement: A DFT study
Zora, Metin (American Chemical Society (ACS), 2004-02-06)
The minimum energy reaction paths and nucleus-independent chemical shifts (NICS) for the Cope rearrangement of cis-3,4-divinylcyclobutene, obtained by (U)B3LYP/6-31G* calculations, are reported. Three transition structures (endo-boatlike, chairlike, and exo-boatlike) have been located, giving rise to formation of cis,cis,cis-, cis,cis,trans-, and trans,cis, trans- 1, 3,5-cyclooctatrienes, respectively. The minimum energy path proceeds through an endo-boatlike, aromatic transition structure. The reaction pat...
Citation Formats
A. Azizoglu, R. Ozen, T. Hokelek, and M. Balcı, “Incorporation of an allene unit into alpha-pinene: Generation of the cyclic allene 2,7,7-trimethylbicyclo[4.1.]octa-2,3-diene and its dimerization,” JOURNAL OF ORGANIC CHEMISTRY, pp. 1202–1206, 2004, Accessed: 00, 2020. [Online]. Available: