4,7,11-Triheterotrishomocubanes – Propeller-Shaped Highly Symmetrical Chiral Molecules Derived from Barrelene

Autor: Sergei I. Kozhushkov, Thomas Preuß, Dmitrii S. Yufit, Stephan Rühl, Yoshio Okamoto, Chiyo Yamamoto, Armin de Meijere, B. Christopher Rinderspacher, Judith A. K. Howard, Peter R. Schreiner, Kathrin Meindl
Rok vydání: 2006
Předmět:
Zdroj: European Journal of Organic Chemistry. 2006:2590-2600
ISSN: 1099-0690
1434-193X
Popis: Epoxidation of barrelene (3) with a neutralized solution of Oxone® gave the barrelene trisepoxide 6 in 82 % isolated yield, while lead tetraacetate promoted aziridination of 3 with two equiv. of N-aminophthalimide gave a mixture of mono-7 and bis(aziridine) endo,exo-8, which were isolated in 67 and 8 % yield, respectively. Fourfold repetition of this aziridination gave the bis(aziridines) exo,exo- and endo,exo-8 along with the trisaziridine 9 in 21, 8 and 19 % yield, respectively. Epoxidation of 7 and endo,exo-8 with buffered m-chloroperbenzoic acid furnished the dioxaazatrishomobarrelene 10 and oxadiazatrishomobarrelene 11 in 36 and 62 % yield, respectively. The structures of triheteratrishomobarrelenes 6 and 9 were established by X-ray crystallography. Upon treatment with BF3·Et2O at –20 °C (for 6) or with the strongly acidic ion exchange resin Amberlyst 15 at ambient or elevated temperatures (for 9–11), these triheteratrishomobarrelenes rearrange to give the triheteratrishomocubanes rac-12 to rac-15, as proved by X-ray crystal structure analysis of rac-13, in 75–100 % yield. The enantiomeric pairs of trioxa- 12 and triazatrishomocubane 13 were separated by preparative HPLC on a chiral column. 12 exhibited specific rotationsof [α]D25 = +196 and [α]36525 = +652 (c = 0.497, CHCl3) for the firstly eluted and [α]D25 = –173 and [α]36525 = –608 (c = 0.503, CHCl3) for the secondly eluted enantiomer; 13 had [α]D25 = +30 and [α]43525 = +501 (c = 0.490, CHCl3) for the firstly as well as [α]D25 = –28 and [α]43525 = –475 (c = 0.501, CHCl3) for the secondly eluted enantiomer. The geometry of rac-13 and the absolute configurations of (–)-12 and (+)-13 were determined by X-ray crystal structure analyses. According to this, (–)-12 and (+)-13 possess the same (1R,3R,5R,6R,8R,10R)-configuration. Theabsolute configuration of the former was also confirmed byDFT computations at the TD-B3LYP/6-31+G(d,p)//B3LYP/6-31+G(d) level of theory; the computed specific rotation for (–)-12 was –178. Computations for the elusive (all-R)-triazatrishomocubane (all-R)-13-H without phthalimidyl substituents on the nitrogen atoms disclosed that the sign of rotation is the same for the parent (all-R)-13-H and (all-R)-trioxatrishomocubane (all-R)-12 with the same absolute configuration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Databáze: OpenAIRE
Externí odkaz: