The adamantane rearrangement of syn‐ and anti‐Tricyclo[4.2.1.1.12,5] decane. Part II. Rearrangements initiated by regioselective formation of carbocations at C(3) and C(9)

Brossi, M.; Ganter, C.

doi:10.1002/hlca.19880710420

Cited by 10 publications

(3 citation statements)

References 26 publications

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“…250-252 "C, rhombic A,, = 0.71069 A, O,,(max) = 27"]; refinement (C, N anisotropic, H isotropic) taking into account 1893 reflections with Fo > 4a(F0); R = 0.060, R , = 0.062. In analogy to the situation in the case of the porphycene 3/2.3-dihydroporphycene pair [7], the transition from 6 to 7 has no noticeable effect on the overall conformation of the ring skeleton (as before, planar). An accurate analysis of the bond lengths suggests that 7 is partially disordered in the crystal [15].…”

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confidence: 81%

Optically Active Isoprene(tricarbonyl)iron(0) and Methyltrimethylenemethane(tricarbonyl)iron(0)

Kappes

Gerlach

Zbinden³

et al. 1989

Angew. Chem. Int. Ed. Engl.

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planar conformation required for oxidation is hindered by non-bonding interactions between the propyl groups and the hydrogen atoms in the 2,7,12,17-positions. The favored hydrogenation of 6 with formation of 5 instead of the expected 7 is probably due to hitherto unexplained kinetic factors, since it is almost certain from the acid-catalyzed tautomerization of 5 to 7 that 7 is the thermodynamically more stable tautomer. , 0. Ermer, ibid. 99 (1987) 909 and 26 (1987) 928. Pyrrolophanes with oppositely disposed pyrrole rings are thus far known only in the form of [2.2](2,5)pyrrolophane and some of its derivatives; see the review by W. W. Paudler, M. D. Bezoari in P. M. Keehn, S. M. Rosenfeld: The furan analogue of 2 is present in the crystal as a planar molecule; E. Vogel, M. Sicken, P. Rohrig, H. Schmickler, J. Lex, 0. Ermer, Angew. Chem. 100 (1988) 450; Angew. Chem. I n / . Ed. Engl. 27 (1988) 411. E. Vogel, M. Kocher, J. Lex, 0. Ermer, Isr. J. Chem. 29 (1989) 257 (David-Ginsburg-Memorial Issue).Comparably short hydrogen bonds between N atoms have, to our knowledge. thus Tar only been observed in "proton sponges" in protonated form, see H. A.

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confidence: 81%

Optically Active Isoprene(tricarbonyl)iron(0) and Methyltrimethylenemethane(tricarbonyl)iron(0)

Kappes

Gerlach

Zbinden³

et al. 1989

Angew. Chem. Int. Ed. Engl.

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“…) anti-2,8,9-Trioxatricyclo[4.2.1.1 2,5 ]decanes are not known. anti-2,8,9-Tricyclo[4.2.1.12,5 ]decane is 23.7 kcal/ mol higher in energy than the isomeric adamantane[68].…”

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confidence: 99%

Functionalised Bicyclic exo‐Glycals by Alkynol Cycloisomerisation of Hydroxy 1,3‐Diynes and Hydroxy Haloalkynes

Miao

Hoffmann

et al. 2005

Helvetica Chimica Acta

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mit den besten W¸nschen herzlich zugeeignet.Functionalised bicyclic exo-glycals are readily obtained by base-catalysed (typically MeONa in MeOH) alkynol cycloisomerisation of ethynylated cyclic saccharides. Thus, base treatment of the phenylethynyl-and halogenoethynylated 1-O-acetyl-ribofuranoses 22 ± 24 and the 4-ethynylated 1-thioglucopyranosides 30 ± 33 gave ± after deacetylation ± selectively the (Z)-configured exocyclic enol ethers 26 ± 28 (84 ± 91%) and 34 ± 37 (63 ± 76%), respectively, resulting from a trans-5-exo-dig cyclisation. The ring closure to the trans-dioxahexahydroindans 34 ± 37 is favoured by a concerted intramolecular protonation of the intermediate vinyl anion by the neighbouring HOÀC(3). Cycloisomerisation of the 6-O-acetyl-4-(phenylethynyl)-1-thio-a-d-glucopyranoside 39 occurred via the corresponding phenylethynylated allenes to provide the galacto-configured (Z)-and (E)-cis-dioxahexahydroindans 40 (30%) and 41 (51%). Surprisingly, the HOÀC(4) unprotected a-dgalactopyranosyl-buta-1,3-diyne 15 and the b-d-glucopyranosyl-buta-1,3-diyne 51 (and its 2-bromoethynyl analogue) undergo a 6-exo-dig ring closure to the 2,5-dioxabicyclo[2.2.2]octanes 16 ± 19 and 52/53, respectively, the ring closure requiring a boat conformation (B 1,4 for 15, 1,4 B for 51). Ring strain (anti-reflex effect) prevents an alkynol cycloisomerisation of 4-(phenylbuta-1,3-diynyl, bromoethynyl, or iodoethynyl)levoglucosan 56 ± 59, and 56 reacted by elimination to the hex-1-ene-3,5-diyne 59 (82%), while isomerisation of 57 and 58 led to epimeric mixtures of the haloallenes 60 (82%) and 61 (68%).Introduction. ± exo-Glycals are versatile synthetic intermediates used for the preparation of, e.g., ulosides [1 ± 3], substituted endo-glycals, and functionalised Cglycosides; their chemistry has recently been summarised by Taillefumier and Chapleur [4] 1 ). Methods for the synthesis of exo-glycals comprise the Wittig-type olefination of glyconolactones and glycosylphosphonium salts, the methylenation of glyconolactones with Tebbe and Petasis reagent, addition ± elimination reaction, reductive elimination of ketopyranosyl bromides, cyclisation of ethenylated alditols induced by electrophiles, followed by elimination, and the Ramberg ± B‰cklund rearrangement of glycosyl sulfones.While alkynol cyclisation (cycloisomerisation) has been used as early as 1959 for the structure elucidation of hydroxylated oligoacetylenes, as illustrated by the highyielding cyclisation of 1 to 2 [9] [10] (Scheme 1), this facile cyclisation has, surprisingly, not been used for the transformation of carbohydrates into exo-glycals, nor has the high yielding base-or Ag

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“…Fe-C24 I.Rll (5). C20-021 1.137 (5), C22-023 1.144 (7). C24-0 2 5 1.126 (6); Fe-C20-021 177.8 (7), Fe-C22-023 179.1 (6).…”

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Optisch aktives Isopren(tricarbonyl)eisen(0) und Methyltrimethylenmethan(tricarbonyl)eisen(0)

et al. 1989

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Ionische Hydrierung von (+)‐1 machte die optisch aktiven Tricarbonyleisen(0)‐Komplexe (+)‐2 und (–)‐3 erstmals zugänglich. Ihre Absolutkonfigurationen wurden aus der Röntgenstrukturanalyse von (+)‐1 abgeleitet, und ihre Enantiomerenreinheit wurde gaschromatographisch an einer mit perpentyliertem γ‐Cyclodextrin belegten Kapillarsäule bestimmt (88 bzw. 96% ee). Die Komplexe sind für asymmetrische Synthesen von Interesse.

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The adamantane rearrangement of syn‐ and anti‐Tricyclo[4.2.1.1.1^2,5] decane. Part II. Rearrangements initiated by regioselective formation of carbocations at C(3) and C(9)

Cited by 10 publications

References 26 publications

Optically Active Isoprene(tricarbonyl)iron(0) and Methyltrimethylenemethane(tricarbonyl)iron(0)

Optically Active Isoprene(tricarbonyl)iron(0) and Methyltrimethylenemethane(tricarbonyl)iron(0)

Functionalised Bicyclic exo‐Glycals by Alkynol Cycloisomerisation of Hydroxy 1,3‐Diynes and Hydroxy Haloalkynes

Optisch aktives Isopren(tricarbonyl)eisen(0) und Methyltrimethylenmethan(tricarbonyl)eisen(0)

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