Table 1 . 'H- and I3C-NMR data of the triquinacenyl cations at -70°C.
`
`'H-NMR (T) in S02CIF
`( a d )
`
`( 9 d )
`
`( 7 d ) ~ ( - 7 )
`
`I3C-NMR (6) in S02CIF [a]
`fa[/)
`
`f 9d,
`
`(711) ~ ( 2 )
`
`
`
`0.95 (A-part; H3, Ha)
`
`2.13 (B-part; H2, H9)
`of an AB system
`
`4.17 (s, H', H6)
`
`4.48 fm. H'O)
`
`1.02 (A-part; Ha)
`1.43 (A-part; H3)
`2.04 (B-part; H2)
`2.06 (B-part; H9)
`of an AB system
`3.99 (A-part; Hs)
`4.19 (B-part; H6)
`4.38 (d. HIo)
`
`5.46 (m, H4, H')
`
`5.22 (m, H')
`
`Pentadienyl
`unit
`
`Olefinic
`positions
`Central
`bridgehead position
`Allyhc
`positions
`
`1.50 (A-part; H3, Ha)
`2.00 (B-part; H2, H9)
`
`252.97 (C')
`195.15 (C', Cs)
`
`137.86 (C', C9)
`
`4.00 (s, H', H6)
`
`134.33 (C', Cb)
`
`4.40 (s, HI")
`
`77.67 (elo)
`
`56.48 (C". C')
`
`243.68 (C')
`195.61 (C8)
`183.28 (C')
`138.70 (C9)
`138.42 (C')
`132.69 (C')
`133.83 (C6)
`84.55 (C'O)
`
`56.46 (C7)
`73.61 (C4)
`
`237.03 (C')
`
`183.92 (C', C8)
`
`132.38 (C', C9)
`132.28 (C', C6j
`
`91.69 (C'O)
`
`72.29 (C4, C7)
`
`[d] Relative to tetramethylsilane.
`
`(9e). A "dehydrotriquinacene"[61 (tricyclo[5.2.1 .04,' 'Ideca-
`1(10),2,5,8-tetraene and/or tricyclo[5.2.1 .04~'0]deca-1 (2),3,5,8-
`tetraene) must occur as an intermediate; the chlorides (4),
`( 5 ) , (6), and especially the dimethylaminotriquinacene (7c),
`may be considered as potential precursors of this class of
`compounds.
`For the generation and investigation of free carbocations
`of the triquinacene system all three chlorides ( 4 ) , (5), and
`( 6 ) were allowed to react with antimony pentafluoride in
`sulfuryl chloride fluoride at - 78 "C and the 'H- and I3C-NMR
`spectra of the reaction mixture were recorded (see Table 1).
`According to these, only the monocations ( 7 d ) [= (2)], (8d),
`and (9d), respectively, were present in each case. Their kinetic
`stability increases with increasing chlorine substitution; thus
`( 7 d ) already decomposes at -4O"C, whereas ( 9 d ) is still
`detectable spectroscopically even after 15 min at 25 "C. Trap-
`ping experiments with sodium methoxide in methanol led
`to the methyl ethers ( 7 b ) , (8b), and (9b), respectively, in
`good yields.
`The ' H- and ' 3C-NMR spectroscopic data of the free car-
`benium ions show that almost planar divinylcarbenium ion
`units are present in these species. Increasing chlorine substitu-
`tion in ( 8 d ) and ( 9 d ) leads to a lowering of the electron
`deficit in the divinylcarbenium ion units and thus to high-field
`shifts of the 'H- and ' 3C-NMR signals.
`Received: June 21, 1976 [Z 495b IE]
`German version: Angew. Chem. 88,610 (1976)
`
`CAS Registry numbers:
`( / ), 6053-74-3; ( 2 ) , 59983-40-3; ( 4 ) , 59991-76-3; (5). 59991-77-4; (6), 59991-
`78-5; ( a d ) , 59991 -79-6; ( 9 d ) , 59991-80-9; tert-butyl hypochlorite, 507-40-4
`[l] 7: Jarobseii, Acta Chem. Scand. 21, 2235 (1967); C . Mercier, P. Soucy,
`W Roseti, and P. Deslongchamps, Synth. Commun. 3. 161 (1973).
`[2] E. D. Stevens, J . D. Kramer, and L. A. Paquette, J . Org. Chem. 41,
`2266 (1976).
`[3] P. Bischof, Angew. Chem. 88, 609 (1976); Angew. Chem. Int. Ed. Engl.
`15, 556 (1976).
`[4] The 'H-NMR, "C-NMR, and mass spectra as well as elemental analysis
`of all the new compounds are in agreement with the given structures.
`[5] See also: K. B. Wiherg, R. K . Barnes, and I . Albin, J. Am. Chem.
`Soc. 79, 4994 (1957).
`[6] A perchlorotricyclo[5.2.1 .04.10]deca-l(10),2,5,8-tetraene was detected by
`7: Jarobsert, Chem. Scr. 5, 174 (1974).
`Cleavage of Ally1 Ethers with Pd/C["]
`By Roland Boss and RolfScheffoid[*]
`Ally1 ethers ( 1 ) are to a large extent stable under basic
`and acid conditions. Because of this property the allyl group
`
`[*] Lic. Chem., R. Boss and Prof. Dr. R. Scheffold
`Institut fur Organische Chemie der Universitat
`Erlachstrasse 9 a, CH-3012 Bern (Switzerland)
`[**I This work was supported by the Schweizerischer Nationalfonds zur
`Forderung der wissenschaftlichen Forschung (Project 2.298-0.74).
`
`is often used as protecting group for alcohols. Removal of
`the protecting group is usually effected by isomerization of
`the allyl ether to the corresponding enol ether ( 2 ) with subse-
`quent H,+ or Hg2+['] catalyzed hydrolysis or oxidative cleav-
`agec21.
`
`Since the known methods131 for allyl ether cleavage did
`not lead to the alcohol (9a) in the case of the glycidonitrile
`allyl ether (9) we investigated the heterogeneously catalyzed
`isomerization of ally1 ethers to cis-enol ethers. We found
`palladium/activated charcoal to be a particularly suitable cata-
`lyst for this purp0se[~1.
`If isomerization is carried out under conditions favoring
`hydrolysis of the cis-en01 ethers the cleavage products alcohol
`and propionaldehyde are obtained directly. Since both the
`catalyst as well as the propionaldehyde (b.p. 49°C) can be
`separated very easily this allyl ether cleavage is very useful
`(cf. examples in Table 1). That the allyl protecting group
`can be selectively removed besides other protecting groups
`is illustrated by the examples glycerol 1 -ally1 2,3-dibenzyl
`ether (7).
`The ally1 ether to be cleaved is heated for a few hours
`at 60" to 80°C in a mixed solvent (see Table 1) in the presence
`of a trace of p-toluenesuifonic acid or mineral acid (e.g. per-
`chloric acid) and a catalytic amount of palladium on activated
`~harcoal'~! In the case of sensitive substrates, e. g. the glyci-
`donitrile (9), the cleavage can be carried out over a prolonged
`period of time (up to ca. 6 days) at room temperature.
`Using
`this method 2,5-dihydrofuran can be cleaved
`smoothly in methanol/water to 4-hydroxybutanol, while 3-
`methoxycyclohexene remains unchanged under comparable
`conditions. This finding would suggest that a cisoid conforma-
`tion of the allyl ether partial structure is a prerequisite for
`the palladium-catalyzed isomerizati~n[~].
`
`Experimental
`Glycerol I,2-dibenzyl ether (712): A solution of ( 7 ) (I.OOg,
`3.2mmol) in methanol (10ml) and water (2ml) is treated with
`palladium/activated charcoal (0.1 g) and toluenesulfonic acid
`(0.1 g). The resulting suspension is boiled under reflux with
`stirring for 24 hours. After removal of catalyst by centrifugation
`the solution is extracted with ether, the solvent removed in
`a rotary evaporator, and the residue distilled. The yield of
`( 7 a ) (b. p. 1 5O0C/O.05 torr[']) is 0.85 g (97 %).
`Methyl 2-(4-hydroxymethyl-2-methoxy-6-oxo-4-vinyl-l-cy-
`clohexeny1)acrylate (8a): To a solution of (8) (3.9 g, 13.3
`mmol) in anhydrous methanol (170 ml) is added palladium/
`
`558
`
`Angew. Chrm. Int. Ed. Engl. / Vol. 15 f 1976) No. 9
`
`Illumina Ex. 1076
`IPR Petition - USP 10,435,742
`
`

`

`f 5 i n . C & - " q
`
`140) C&-OH
`
`15u/ n-CsH,,-OH
`
`PdjC methanol/H20/H
`6 h reflux
`Pd/C methanol/H20/H+
`6 h reflux
`
`+
`
`Pd/C H,O/Hi
`6 h X0"C
`
`PdjC methanol/H20/H+
`24 h reflux
`
`Pd/C anhydrous methano1,'TsOH
`20 h reflux
`
`180) H Q , b < , H 3
`
`0 cooc11,
`
`Pd/C dioxaneiH,O/H
`6 days room temperature
`
`+
`
`PdjC ethanol/H,O/H
`3 h reflux
`
`+
`
`> 95
`
`> 95
`
`> 95
`
`84
`
`78
`
`~
`
`_ _ _ _ _ _ ~-
`[a] Where not stated otherwise perchloric dcid in concentrdtions of I to 5 mmol/ether was used as acid (H')
`[b] The yield5 refer to isolated material
`
`~
`
`activated charcoal (0.6 g) and p-toluenesulfonic acid (0.3 g)
`and the stirred suspension boiled under reflux for 20 hours.
`After removal of the catalyst by filtration, the filtrate is concen-
`trated to half its original volume in a rotary evaporator,
`treated with saturated NaCl solution and ice, and extraced
`five times with dichloromethane. After removal of solvent
`in a rotary evaporator there remains a pale yellow oil which
`crystallizes on drying in a high vacuum. Melting point after
`a single recrystallization from ether: 87 to 89°C. Yield 3.0g
`(84 %).
`
`[Z 497 IE]
`Received: July 15, 1976
`German version: Angew. Chem. 88,57X (1976)
`
`CAS Registry numbers:
`(4). 1746-13-0; (4a), 108-95-2; (51,3295-97-4; ( 5 u ) , 1 1 1-87-5; (6), 123-34-2:
`( 6 u ) , 56-87-5; (7), 59991-88-7; ( 7 a ) . 59991-89-8; ( 8 ) , 59991-90-1: ( X u ) ,
`59991-91-2; ( 9 ) , 59991-92-3: (9u), 59991-93-4; ( l o ) , 20860-14-4; ( I O U ) , 58-
`22-0: palladium 7440-05-3
`
`~
`
`~. -
`[I] R . Gigg and C . D. Wurren, J. Chem. Soc. C1968, 1903.
`[2] J . Cunmngiium, R . Cigg, and C . D. Wurren, Tetrahedron Lett. 1964,
`1191.
`131 7: J. Prosser, J. Am. Chem. SOC. 83, 1701 (1961); C. C. Price and W
`H . Snvder, ihid. 83, 1773 (1961); H . C. Clork and H . Kurosuna, lnorg.
`Chem. 12, 357, 1566 (1973); E. J . Corey and J . W Suggs, J. Org. Chem.
`38. 3224 (1 973).
`[4] Weused the hydrogenation catalyst 10 %palladium on activated charcoal
`obtainable from Fluka. Experiments with rhodium on activated charcoal
`also gave positive results; ruthenium and platinum on activated charcoal
`proved less useful. This is in agreement with the finding that palladium
`proves to have the greatest tendency for shifting double bonds in hydro-
`genations. Cf. also P . N . Rylawder, Adv. Chem. Ser. 9X, 150 (1971).
`[5] As is to be expected the allyl cleavage is blocked by traces of "catalyst
`poisons"such as thiophenol and pptassium cyanide. It is therefore recom-
`mended that the reaction vessel be cleaned with chromic sulfuric acid,
`washed with potassium hydroxide solution, and finally rinsed with
`demineralized water.
`
`Angcw. Chem. Int. Ed. Engl. 1 !-+I/. 15 (1976) No. 9
`
`Synthesis of cis-Trioxa-tris-o-hornotropilidene[**]
`By Horst Prinzhuch and Christoph Riickeri'l
`Preparative and mechanistic objectives stimulated extension
`of our work on the tris-o-homobenzenes (1) (X=CR2, 0,
`NR, S)"] to investigation of the homologs ( 2 ) - ( 4 ) . After
`having recently described the first valence isomeric o/rr-hexa-
`homobenzenes (4)['], we now report the dioxa-bis- and trioxa-
`tris-o-homotropilidenes (2) (X = O)I3].
`
`Mainly because of our particular interest in the stereoelec-
`tronic features of valence isomerization in the cis-trioxide
`( l o ) , we have commenced our study program in this area
`with an investigation of the chances and stereoselectivity of
`a stepwise epoxidation of tropilidene. On reaction of excess
`peroxy acid (peroxyacetic acid, m-chloroperoxybenzoic acid)
`with the readily accessible oxide (5)14] in dichlorometh-
`ane/Na2C03 the four dioxides (6)-(9)
`are formed, whereby
`the dioxide (6) is, according to a capillary-GC/MS analysis,
`the least favored product (total yield of products up to 40 %,
`ratio in a typical experiment cu. 6 : 26 : 27 : 41). Preparative
`gas chromatography affords pure (7) and a mixture of ( 8 ) / ( 9 )
`- _ _
`[*] Prof. Dr. H. Prinzbach and Dipl.-Chem. Ch. Rijcker
`Lehrstuhl fur Organische Chemie der Universitat
`Albertstrasse 21, D-7800 Freihurg (Germany)
`[**] This work was supported by the Deutsche Forschungsgemeinschaft
`and the Fonds der Chemischen Industrie. The authors are indebted to Dr.
`If. Fritz and Dr. W Richter, respectively, for the N M R and GCIMS analyses.
`Ch. Riicker thanks the Studienstiftung des Deutschen Volkes for a graduate
`study grant.
`
`559
`
`