Cycloadditions to alkenyl[2.2]paracyclophanes

FULL PAPER

DOI: 10.1002/ejoc.200500396

Cycloadditions to Alkenyl[2.2]paracyclophanes^[‡]

Ashraf A. Aly,^[a]Sonja Ehrhardt,^[a]Henning Hopf,*^[a]Ina Dix,^[a]and Peter G. Jones^[b]

Keywords: Cyclophanes / Cycloadditions / Annelation / Ene reaction

Cycloadditions between the 4-alkenyl[2.2]paracyclophanes

7, 16–21 and the dienophiles 10a–h have been studied.

the vinyl substituent (10f, h). Several of the isolated cycload-

ducts (e.g. 24–26, 52) are valuable substrates for the prepara-

Whereas 10a, b, d, and g prefer Diels–Alder addition involv- tion of annelated cyclophanes. The mechanisms of several of

ing the olefinic double bond and one double bond of a cy-

clophane benzene ring, 10c, e, f, and h undergo other cyclo-

additions such as ene reaction (10c), [2+2] cycloaddition to

the olefinic double bond (10e) and heterodiene addition to

these cycloadditions are discussed.

Germany, 2006)

the dienophile (general structure 10) must carry appropriate

groups. The adducts 11 thus obtained can subsequently be

aromatized to 12 or be used in other transformations

(Scheme 2).

In the present study we describe the addition of the

dienophiles 10a–h to 7 and several other 4-alkenyl[2.2]para-

cyclophanes.

Introduction

Cycloadditions – predominantly of the Diels–Alder

type – play an important role in [2.2]paracyclophane chem-

istry. Thus tetra- or disubstituted cyclophanes 3 are ob-

tained by the cycloaddition of triple bond dienophiles 2 to

1,2,4,5-hexatetraene (1),^[2–4]the tandem process beginning

with a [2+4] cycloaddition to produce a p-xylylene, which

subsequently dimerizes in a [6+6]process to the target mole-

cule 3. Depending on the substituents R, this can be linearly

or angularly annelated to 4^[5]and 5,^[6]respectively, or pro-

vide unusual adducts such as the bis-barrelene 6,^[7,8]all

three processes involving cycloadditions in their decisive

steps (Scheme 1).

In our previous studies in this series we have demon-

strated how these cycloadducts can be used to prepare novel

layered π-systems,^[9]new chiral compounds^[10]or serve as

substrates for further transformations.^[11]To learn more

about the mechanistic and preparative details of these cy-

cloadditions, we decided to investigate one of the simplest

processes of this type: the addition of various double and

triple bond dienophiles to a selection of 4-alkenyl[2.2]para-

cyclophanes. Indeed, the addition of the simplest diene of

this type, 4-vinyl[2.2]paracyclophane (7) itself to dehy-

drobenzene (8), provided access to the phenanthrenophane

9, the parent molecule of the angular systems.^[6,12]In order

to introduce functional groups into 9 and its derivatives,

Preparation of the 4-Alkenyl[2.2]paracyclophanes

The olefinic dienes were prepared from [2.2]paracyclo-

phane (13) by standard methods as summarized in

Scheme 3. Thus the known carbonyl precursors 14^[13]and

15^[14]were either converted by Wittig reactions into the ole-

fins 7, 16 and 17 or into 18–21 by Grignard reactions fol-

lowed by acid-catalyzed dehydration (Scheme 3). The struc-

ture assignment (see experimental) was also straightfor-

ward; whenever diastereo- and regioisomers were produced,

these were separated by column chromatography or HPLC.

Cycloaddition Reactions

a) Maleic Anhydride (10a): Heating of 7 in the presence

of 10a at 120 °C for 5 days in acetic acid results in the for-

mation of a single adduct in 72% yield. According to the

spectroscopic data given in the Exp. Sect. we assign struc-

ture 24 to this product. Since 7 is chiral – the drawn struc-

ture has S configuration – and two new stereogenic centers

are produced during the process, in principle a mixture of

diastereomers could be formed. That this is not the case,

i.e. that the addition is diastereospecific, can be rationalized

by the addition mechanism presented in Scheme 4.

[‡] Cyclophanes, LIV. Part LIII: Ref.^[1]

[a] Institut für Organische Chemie, Technische Universität

Braunschweig,

Hagenring 30, 38106 Braunschweig, Germany

Fax: +49-531-391-5388

E-mail: H.Hopf@tu-bs.de

[b] Institut für Anorganische und Analytische Chemie, Technische

Universität Braunschweig,

Although the conformation of 7 is unknown, we assume

that the required cis orientation shown in the Scheme can

be achieved readily. The dienophile can then attack the aro-

Postfach 3329, 38023 Braunschweig, Germany

Fax: +49-531-391-5387

E-mail: p.jones@tu-bs.de

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Scheme 1. [2.2]Paracyclophanes as starting materials for novel layered organic compounds.

Scheme 3. Preparation of 4-alkenyl[2.2]paracyclophanes.

least its partial intercalation between the two benzene rings,

which is highly unlikely, considering that the intraannular

distance between the decks in the cyclophane amounts to

only ca. 310 pm. Reaction from the sterically less shielded

exo-side furnishes adduct 22, with the anhydride ring

pointing away from the phane system. Under the acidic

Scheme 2. Cycloadditions to 4-alkenyl[2.2]paracyclophanes.

matic diene either from the inner or from the outer side of conditions, 22 will be protonated to the cyclohexadienyl cat-

the layered system, and clearly the latter route should be ion – a σ complex, incidentally, generated by protonation

favored. To allow “internal” attack of 10a would require at outside the six-membered ring – which receives transannu-

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Cycloadditions to Alkenyl[2.2]paracyclophanes

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other alkenyl derivatives 18–21 reacts with 10a. Even after

prolonged heating (up to 2 weeks) in high-boiling solvents

(acetic acid, toluene) the substrate dienes were recovered

unchanged, the only products formed being uncharacteriz-

able “polymeric products”. Apart from the increased diffi-

culty with which these dienes achieve the cisoid-conforma-

tion, this lack of reactivity could also result from the fact

that all dienes in this series carry an alkyl group in 1-posi-

tion of the olefinic substituent. In the decisive, rate-de-

termining initial step (cf. 7 Ǟ 22) this substituent will be

forced into close vicinity to one of the ethano bridges. Be-

cause of the rigid structure of the phane nucleus, steric com-

pression in the primary adduct cannot be released to the

same extent as in an “open” system. For example, α-methyl-

p-methylstyrene is known to add maleic anhydride (10a) in

acetic anhydride at 80 °C in the presence of N,N-dimeth-

ylaniline within 24 h.^[19]Likewise, 1,1-diphenylethene reacts

readily with 10a (refluxing benzene, 4 h).^[20]

b) Dimethyl Acetylenedicarboxylate (10b): Not surpris-

ingly, the cycloaddition behavior of 10b towards 7 and 16

resembles that of 10a. Thus, heating the parent system 7

and 10b in glacial acetic acid at 120 °C for 3 days yields

the dihydronaphthalenophane derivative 26a in 72% yield,

easily identified by its spectroscopic data and chemical be-

havior (see below, Scheme 5).

Scheme 4. Cycloadditions of 4-alkenyl[2.2]paracyclophanes and

maleic anhydride.

lar stabilization from the intact benzene ring. Such an inter-

action has been described many times in cyclophane chem-

istry^[15]and also been observed directly by protonation of

[2.2]paracyclophane in superacidic media.^[16]Finally, depro-

tonation regenerates the paracyclophane system and fur-

nishes the Diels–Alder adduct 24. The shown stereochemis-

try is supported also by the chemical shifts of the bridge

protons in the immediate vicinity of the anhydride ring. If

this ring was positioned in endo orientation (pointing

towards the unaffected benzene ring), one of its carbonyl

groups would be close to one of the bridge protons, causing

a shift to lower field. This effect has been observed for

several derivatives of [2.2]paracyclophane carrying a car-

bonyl-containing substituent in the 4-position.^[17]In all

these cases the methylene proton facing the carbonyl func-

Scheme 5. Cycloadditions of 4-alkenyl[2.2]paracyclophanes and di-

methyl acetylenedicarboxylate.

Similarly, 16 and 10b provide the 1:1 adduct 26b (acetic

tion is shifted to approximately δ = 4.0 ppm, whereas all acid, reflux, 41% yield). When a mixture of 16 and 17 is

other bridge protons absorb below δ = 3.8 ppm. For 24 all used in this reaction, only the E diastereomer reacts. The

bridge protons appear as complex multiplets between δ = orientation of the methyl substituent (δ = 0.88 ppm, J =

3.7 and 2.75 ppm (see Exp. Sect.).

6.9 Hz) follows again from a Nuclear Overhauser experi-

Cycloaddition between the propenyl derivative 16 in ace- ment as described for 25. In contrast to the above cycload-

tic acid (5 d, 120 °C) and maleic anhydride (10a) also leads ditions with 10a, the Diels–Alder addition of 18 and 10b

to one product only (54%).^[18]To this adduct structure 25 (acetic acid, 5 d) furnishes the cycloadduct 26c in 51%

is assigned, the main arguments again being the approach yield. If the orientation of R³and the hydrogen atom at

of 10a to the diene as described above for the parent system the same carbon atom were reversed, we would expect an

and the absence of a Nuclear Overhauser effect on the fac- Overhauser effect at 13-H on saturation of the methyl signal

ing aromatic protons when the signal for the methyl group (δ = 0.92 ppm, J = 7.2 Hz). This, however, is experimentally

(δ = 1.00 ppm, J = 6.5 Hz) is saturated. If the methyl group not observed, thus the relative orientation is as shown in

pointed towards the interior of the adduct, i.e. towards the Scheme 5. The reason for this enhanced reactivity of 18/10b

unsubstituted benzene ring, a NOE enhancement could be compared to that of the maleic anhydride (10a) addition is

expected for the aromatic protons 12- and 13-H, respec- not clear at present. Molecular models indicate that, with

tively; according to molecular models the methyl group and the additional double bond in the newly created six-mem-

these protons are very close to each other. None of the bered ring, the methyl substituent is farther away from the

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ethano bridge in the primary adduct. When a mixture of

All other olefins (16, 17, 19–21, employed as a mixture of

19–21 is heated with 10b in acetic acid for several days, no isomers) also reacted with 10c in varying yields (30–60%),

cycloaddition takes place and the starting olefins are reco- however, in no case could we isolate pure addition products

vered unchanged.

from the oily mixtures either by recrystallization or column

c) Diethyl Azodicarboxylate (10c): Heating various sty- chromatography. Mass spectra of these raw adducts indi-

rene derivatives with diethyl azodicarboxylate (10c) leads to cated the formation of 1:1 products, but their precise struc-

the expected adducts, Diels–Alder products being produced tures could not be determined. In the case of 20 and 21 the

initially, which stabilize themselves subsequently by an ene possibility exists that ene reactions at two different methyl

reaction.^[21]In contrast, neither 7 nor its methyl derivative substituents can take place, possibly a reason for the ob-

18 yield the expected adducts. The parent system 7 provides served product complexity.

the oxadiazine 27 on treatment with 10c in toluene at room

d) N-Phenyltriazolinedione (10d): The addition of the “re-

temperature for 7 days in the presence of trichloroacetic cord dienophile” 10d to 17 provides further insight into the

acid in 18% yield, 21% of the starting material being reco- mechanism of the Diels–Alder additions to vinyl[2.2]para-

vered; if acetic acid is used as the solvent no cycloaddition cyclophanes. When these two components are reacted with

occurs (Scheme 6).

each other at room temperature for 7 days in the presence

of catalytic amounts of trichloroacetic acid, a 2:1 adduct

results in 65% yield, to which we assign the bis-urazole

structure 34 (Scheme 7).

Decisive for the assignment are the bridgehead proton at

C-6 and the olefinic protons at carbon atoms 8 and 17. The

6-H is registered at δ = 5.96 as a doublet with J = 6.3 Hz,

indicating a vicinal coupling partner in cis-orientation (5-

H, δ = 5.51, m). In the ¹³C off-resonance spectrum these

two carbon atoms absorb as doublets at δ = 60.14 and

58.78 ppm. The proton at C-8 at δ = 4.9 is slightly shifted

up-field because of the anisotropy of the facing intact ben-

zene ring and split into a doublet (J = 2.2 Hz) because of

the homoallylic coupling with 5-H; 17-H is registered as a

multiplet at 6.22 coupling with its neighboring methylene

group (18-H) and 5-H. In the off-resonance ¹³C spectrum

these two olefinic carbon atoms absorb as doublets at δ =

123. 47 and 123.74. The complete spectroscopic data of 34

are given in the Exp. Sect.

Scheme 6. Cycloadditions of 4-alkenyl[2.2]paracyclophanes and di-

ethyl azodicarboxylate.

As structure 27 shows, a [2+4] cycloaddition has also

We explain the formation of this bizarre product by the

taken place in this case; however, the cyclophane has re- following route (Scheme 7). Initial monoaddition destroys

acted as the dienophile and the N=N–C=O grouping of 10c the aromatic character of the substituted benzene ring of 7

plays the role of the diene. That azodicarboxylates react in and provides the adduct 29. Since 10d is reactive enough, it

this manner has been described in the literature several outpaces the aromatization of 29 – as described above for

times, a typical example being indene, which also furnishes the addition of 10a and 10b – and adds a second equivalent

an oxadiazine with 10c.^[22,23]Although the connectivity of of 10d to provide the 2:1 product 30. If this had been the

27 can be derived unambiguously from our spectroscopic final adduct, its spectra would have shown three monosub-

data of the cycloadduct (see Exp. Sect.), its relative stereo- stituted olefinic carbon atoms and no bridgehead hydrogen

chemistry cannot. Since in the cycloaddition a new ste- atom, rather than the observed two =CH groups and one

reogenic center is produced, we would expect the formation bridgehead hydrogen atom (see above and Exp. Sect.).

of diastereomers in the process. These, however, were not We therefore postulate that the addition reactions are fol-

observed. Since it is especially unlikely that the NMR sig- lowed by an isomerization process. In this a proton first

nals of both diastereoisomers are identical, we have to as- adds to the C7–C8 double bond of 30 and the resulting

sume that the reaction occurs with very high diastereoselec- cation 31 undergoes a Wagner–Meerwein rearrangement,

tivity.

leading to the less strained carbenium ion 32. Acid-cata-

With the reaction between the isopropenyl derivative 18 lyzed rearrangements of [2.2]paracyclophanes into [2.2]-

and 10c, a third cycloaddition type is observed for the 4- parametacyclophanes are a well-documented phenomenon

alkenyl[2.2]paracyclophanes: the ene reaction. Under the in cyclophane chemistry.^[26]Intermediate 32 subsequently

same conditions as above the 1:1 adduct 28 is obtained in undergoes a 1,2-hydrogen shift to the tertiary cation 33,

30% yield, and again the addition is incomplete (recovery which on loss of a neighboring proton ultimately provides

of 18: 31%). In the spectra of 28 the terminal double bond the isolated adduct 34. The reaction of styrene with the aza-

is easily identifiable. The ene-reaction of azodicarboxylates dienophile 10d has been investigated by several au-

with sterically hindered dienes has been described in the thors;^[27,28]it leads to a mixture of two 2:1 adducts, the one

literature.^[24,25]

corresponding to 30 (without the phane bridge), the other

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Cycloadditions to Alkenyl[2.2]paracyclophanes

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Scheme 7. Cycloaddition of 4-vinyl[2.2]paracyclophane and N-phenyltriazolindione.

a product of a tandem sequence beginning with the ad- C-17 and the neighboring benzene ring. In Scheme 8 the

dition of one equivalent of 10d (cf. structure 29) followed intermediacy of diradical intermediates is postulated. Not

by an ene reaction that regenerates the aromatic ring.

only can 10e approach the cyclophane from the outside (see

e) Tetracyanoethene (10e): Surprisingly, the addition of above) or the inside of the phane system but the vinyl sub-

10e, one of the most frequently employed dienophiles, to stituent can assume two different orientations: cisoid, as

the parent hydrocarbon 4-vinyl[2.2]paracyclophane (7) does shown in 7 and mandatory for a Diels–Alder type reaction,

not yield the expected [2+4] cycloadduct 40. Rather, after and transoid, as illustrated by conformation 35. Assuming

stirring a mixture of the two components in glacial acetic that outside attack is favored as discussed for the addition

acid for three days at room temperature, a product is ob- of 10a and b, conformation 35 would lead to the S,R-dia-

tained in 33% yield that, according to its spectroscopic stereomer 37 involving diradical 36, or, alternatively, from

data, must contain a four-membered ring. In particular, a 7 via 38 to the S,S-diastereomer 39. Although only one dia-

doublet at δ = 45.69 and a triplet at 35.23 in the off-reso- stereomer is produced in the reaction, no distinction be-

nance ¹³C NMR spectrum are of diagnostic value (C-17 tween these two alternatives is possible at present. The ac-

and C-18), and a doublet of doublets at δ = 4.59 (J₁= 8.4, tual conformation of 4-vinyl[2.2]paracyclophane is un-

1

J₂= 12.1 Hz) in the H spectrum, caused by the proton at known. However, according to a MP2/6-31 G(d) surface

C-17. The multiplet for the methylene group of the four- scan, conformation 7 is more stable than 35 by about

membered ring overlaps with the signals of the bridge meth- 2.5 kJ/mol.^[32]

ylene groups and hence cannot be analyzed. All other

Cycloaddition of 10e to the isopropenyl cyclophane 18

NMR signals (see Exp. Sect.) support this structure pro- (room temperature, acetic acid, 2 d) provides another 1:1

posal. For the [2+4] cycloadduct 40 not only would the mul- adduct in good yield (81%), shown to possess the cyclobu-

tiplicity of the signals have been different, but the ratio of tyl structure 41. The signal of the methyl group at δ = 2.29

the aromatic to the non-aromatic protons would have been is sharp, indicating again the highly diastereoselective na-

6:12 rather than the observed 7:11. Since none of the ¹³C ture of the addition. The fact that the ring-forming process

NMR signals shows any doubling, we can assume that only takes place stepwise was shown by the addition of 10e to

one diastereomer, either 37 or 39, has been formed in the the pure diastereomer 20, which was isolated from the

cycloaddition, excluding the unlikely possibility that these above product mixture (see Scheme 3) by gas chromatog-

products possess identical ¹³C NMR spectra (Scheme 8).^[29]raphy. In the adduct 42 the two methyl groups are registered

[2+2] cycloadditions of 10e to various double bond sys- as two doublets (δ = 1.66, J = 7.0 Hz and δ = 1.76, J =

tems have been described in the literature several times,^[30,31]6.9 Hz, methyl substituents at C-18) and two singlets (δ =

and they take place in a stepwise fashion involving either 2.16 and 2.17 ppm, methyl substituents at C-17), demon-

diradical or dipolar intermediates. Regardless which mode strating that the stereochemical information of the starting

is preferred in the case of 7 and 10e, the bond between the olefin has been lost.^[33]Conventional electron-rich styrenes

terminus of the alkene (C-18) and 10e will be formed first, such as 4-methoxy-1-propenylbenzene have also been

since this process results in the more stable intermediate, shown to add 10e (room temperature, tetrahydrofuran) with

even if there is no perfect overlap between the orbital at formation of cyclobutane derivatives.^[34]

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Scheme 8. Cycloadditions of 4-alkenyl[2.2]paracyclophanes and tetracyanoethene.

f) 3,4,5,6-Tetrachloro-1,2-benzoquinone (10f): ortho-Qui- double doublets for the hydrogen atoms in the dioxane ring

nones are interesting addition partners since in principle at δ = 4.02 (J = 11.8 and 9.0 Hz), 4.52 (J = 11.8 and 2.3

they can provide two diene systems: the endocyclic all-car- Hz), and 5.34 (J = 8.9 and 2.3 Hz), corresponding to 3-H,

bon diene unit and the semicyclic α-diketo grouping. In a 3-HЈ and 2-H, respectively. In the ¹³C NMR spectrum, the

classical investigation Horner and Merz showed that the carbon atoms C-2 and C-3 resonate at δ = 73.09 and

mode of addition is strongly influenced by the nature of 68.53 ppm, and appear as a doublet and a triplet, respec-

the dienophile.^[35]When, for example, styrene and 10f are tively, in the off-resonance spectrum. In the case of 48, the

brought to reaction, the butadiene systems “wins” and the ¹H NMR spectrum revealed two doublets at δ = 1.00 (J =

bicyclic diketone 43 is obtained as the 1:1 cycloadduct. On 6.3 Hz) and 4.52 (J = 8.0 Hz), assigned to the methyl and

the other hand, introduction of a second phenyl group in 2-H protons, while the 3-H proton appears as a multiplet

the 1-position (1,1-diphenylethene) favors the formation of at δ = 4.12–4.18 ppm. The observed ¹³C NMR signals of

the benzodioxane 44. Whereas indene and phenylacetylene 48 confirm its proposed structure by the appearance of the

lead to adducts of the former type, tolane again furnishes a three methyl groups at δ = 15.87, 25.08, and 25.23 ppm,

benzodioxane derivative; with 1,3-cyclopentadiene a mix- respectively. The two distinctive carbon atoms C-2 and C-3

ture of the two types of adducts is produced. Since struc- of the dioxane ring resonate at 67.69 and 76.55 ppm. The

tural and spectroscopic data of either of these adducts are complete NMR data together with the other spectroscopic

lacking in the chemical literature, we first reacted (toluene, data, all supporting the given structural assignment of the

reflux) 10f with 2,5-dimethylstyrene (45) and (E)-2-pro- two adducts, can be found in the Exp. Sect. Further structure

penyl-p-xylene (46), respectively, as model compounds, hy- proof, including the relative configuration of 48, rests on the

drocarbons that can be considered as “halves” of [2.2]para- single-crystal X-ray structures of 47 and 48 discussed below.

cyclophanes. In both cases benzodioxanes, 47 and 48, are

produced as the sole adducts in acceptable yields furnishes a single diastereomer in 62% yield to which we

(Scheme 9). assign structure 49 according to its spectroscopic and ana-

The cycloaddition (refluxing toluene, 2 days) of 10f to 7

The most characteristic feature of 47 and 48, the hetero- lytical data (see Exp. Sect.). The structure displayed in

cyclic ring, is easily identified by its NMR spectra. For ex- Scheme 9 is the result of an “outside” attack of 10f on the

1

ample, the H NMR spectrum of adduct 47 shows three cisoid dienophile, 7; it possesses S configuration at its chiral

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Scheme 9. Cycloadditions of styrene derivatives and 3,4,5,6-tetrachloro-1,2-benzoquinone.

center. Supporting information on the stereochemical tor x, –1 + y, z], Cl3···Cl1 [3.645 Å, 1½ – x, ½ + y, ½ – z]

course of the [2+4] cycloaddition is obtained when 16 is and C3–H3B···Cl4 [2.76 Å, 159°, x, –1 + y, z], and in 48

reacted with 10f under the same conditions. Now, cycload- Cl2···Cl2 [3.342 Å, 1 – x, 2 – y, 1 – z].

duct 50 is formed in 71% yield, the structure of which not

only follows from its spectroscopic data (see Exp. Sect.) but the cyclohexane molecule is well ordered and displays crys-

also from an X-ray structural analysis. tallographic inversion symmetry. The configuration of the

Compound 50 crystallizes as a cyclohexane hemisolvate;

The structure of compound 47 is shown in Figure 1 and substituents across the single bond of the benzodioxane

of 48 in Figure 2, in which the E (trans) geometry across ring is trans as in 48 (Figure 3). The molecules associate

the single bond C2Ј–C3Ј is clearly shown. The most striking through several short contacts, in particular the C–H···π

intermolecular contacts in 47 are Cl3···O4 [3.340 Å, opera- contacts C2Ј-H2Ј···centroid(C12,13,15,16) [2.64 Å, 165°,

Figure 1. The structure of adduct 47 in the crystal.

Figure 2. The structure of adduct 48 in the crystal.

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operator ½ – x, –½ + y, 1½ – z], Cl2···Cl3 [3.542 Å, –1 – x,

As usual, the structural assignment of 52 is indicated by

1 – y, 1 – z] and C9–H9B···Cl4 [2.77 Å, 137°, ½ – x, –½ + the spectroscopic data of the adduct. In the ¹H NMR spec-

y, 1½ – z].

trum the multiplets for the ethano bridge protons and the

methylene groups at C-17 and C-18 overlap, but the ¹³C

signals (triplets) for the corresponding carbon atoms are

clearly resolved (δ = 20.09 and 26.40 ppm for C-17 and C-

18, and δ = 33.49, 34.53. 34.92. 35.28 ppm for the ethano-

bridge carbon atoms). On the basis of COSY H,H and C,H

spectra all signals could be unambiguously assigned and the

appropriate chemical shifts can be found in the Exp. Sect.

With the efficient π-acceptor 10h, compound 7 also un-

dergoes a high-yielding cycloaddition (refluxing toluene,

3 days) providing the 1:1 adduct 53 in 93% yield. Its NMR

spectra resemble those of related adducts (e.g. 39, 49); in

particular the protons at C-17 and C-18 are easily assigned.

One of the latter is registered at δ = 2.75 ppm as a doublet

of doublets with J = 15.2 and 11.6 Hz, whereas the signals

of the other proton at this position overlaps with the mul-

tiplets of the ethano bridges of the cyclophane. On the

other hand 17-H appears at δ = 5.42 ppm as double doublet

with J = 11.6 and 1.3 Hz. In the ¹³C NMR spectrum the

dihydro-2H-pyran ring is characterized by absorptions at δ

= 25.90 (C-18), 36.50 (C-19), 78.65 (C-17), 97.68 (C-20),

and 175.95 (C-21) ppm. To rationalize the observed regiose-

lectivity, we again postulate that the cisoid olefin (e.g. con-

formation 7) is attacked from the “outside” of the phane

system.

Figure 3. The structure of adduct 50 in the crystal.

g) (E)-1,2-Dibenzoylethene (10g), 2-Dicyanomethylenin-

dan-1,3-dione (10h), and Other Dienophiles: Exploratory ex-

periments were undertaken with 10g and 10f as well as se-

veral other functionalized dienophiles. Whereas addition of

acrylonitrile, fumaronitrile, 1,2-bis(phenylsulfonyl)ethene,

propinal and (p-tolylsulfonyl)acetylene to 7 failed – in most

cases these dienophiles decomposed under the compara-

tively harsh reaction conditions – refluxing an equimolar

mixture of 7 and 10g in acetic acid/acetic acid anhydride

for 3 days resulted in the formation of the furan 52 in 91%

yield. Clearly, the primary adduct 51 does not survive the

reaction conditions and cyclizes under dehydration to 52,

a reaction that has often been observed for 1,4-diketones

(Scheme 10).

Further Transformations of the Cycloadducts

The above transformations not only illustrate that 4-alk-

enyl[2.2]paracyclophanes can participate in a wide spectrum

of cycloaddition reactions ([2+4]- and [2+2] cycloadditions,

ene reactions, additions to heterodienophiles), but also that

the isolated adducts can be used as substrates for further

investigations in cyclophane chemistry. In particular, some

of the adducts are useful intermediates for functionalized

annelated cyclophanes, opening up new routes for the prep-

aration of novel helicenes^[36]as illustrated in Scheme 11.

As expected, the aromatization of the anhydrides 24 and

25 and the diesters 26a–c with DDQ in refluxing chloroben-

zene did not cause any problems. The naphthalenophane

anhydrides 54a and b and the diesters 55a–c were obtained

in acceptable yields, and their structures proved by the usual

analytical methods (see Exp. Sect.). Oxidation of the furan-

ophane 52 was even achieved in near quantitative yield. The

resulting product 56 is already a helicenophane, and the

possible preparation of these derivatives in the carbocyclic

series is illustrated in the last line of scheme 11, applying a

route previously developed by us for linear annelation of

[2.2]paracyclophanes.^[5]Reduction of 55a to the diol and

subsequent treatment with phosphorus tribromide could

provide a dibromide that, on reduction with zinc, could

yield the ortho-xylylene intermediate 57. In the presence of

a dienophile such as 10b, this would be trapped to a Diels–

Alder adduct that could be aromatized as described above.

The resulting benzolog 58 of 55a could be resubjected to

Scheme 10. Cycloadditions of 4-vinyl[2.2]paracyclophane and mis-

cellaneous dienophiles.

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Cycloadditions to Alkenyl[2.2]paracyclophanes

FULL PAPER

Scheme 11. Aromatization of the primary adducts between 4-alkenyl[2.2]paracyclophanes and various dienophiles.

reaction from ethyl(triphenyl)phosponium bromide and 2,5-di-

methylbenzaldehyde (Aldrich).

the same sequence or the intermediate be trapped by other

dienophiles. Cylophanes containing differently substituted

aromatic “decks” are not readily prepared by the routes of

traditional cyclophane chemistry. The approach presented

here thus offers a potentially useful alternative.

1. Preparation of 4-Alkenyl[2.2]paracyclophanes

a) 4-Ethenyl[2.2]paracyclophane (7): To a suspension of methyl(tri-

phenyl)phosphonium bromide (27.2 g, 76.2 mmol) in 250 mL of

anhydrous tetrahydrofuran was added at 0 °C 40 mL (76.2 mmol)

of n-butyllithium (1.9 m in n-hexane). After stirring at room temp.

for 2 h a solution of 4-formyl[2.2]paracyclophane (14)^[13](12.0 g,

51.0 mmol) in 300 mL of tetrahydrofuran was added at 0 °C to the

ylid solution. The reaction mixture was stirred at room temp. over-

night and hydrolyzed under ice cooling with ca. 200 mL of water.

The solution was concentrated to ¼ of its volume and extracted

thoroughly with dichloromethane. The combined organic phases

were washed with water, dried with sodium sulfate and the solvents

were removed in vacuo. The oily residue was purified by silica gel

column chromatography with dichloromethane: 9.8 g (82%) of 7,

colorless needles (petroleum ether), m.p. 78 °C. ¹H NMR: δ = 2.72–

3.53 (m, 8 H, ethano bridges), 5.17–5.61 (m, 2 H, =CH₂), 6.29–

6.95 (m, 8 H, Ar-H and Ar-CH=) ppm. ¹³C NMR: δ = 33.60,

34.61, 35.16, 35.41 (t, C-1,-2,-9,-10), 114.14 (t, =CH₂), 129.15,

130.12, 131.77, 131.90, 132.97 (2×), 134.71, 135.19 (d, C-5,-7,-8,

-12,-13,-15,-16, -CH=), 137.76, 137.85, 139.25 (2×), 139.73 (s, C-3,

Experimental Section

General Remarks: Melting points: Kofler hot stage, uncorrected.

¹H NMR and ¹³C NMR spectra: in CDCl₃, chemical shifts relative

to internal TMS; Bruker AM-300 (300.1 and 75.5 MHz), WM-400

and Bruker AM-400 (400.1 and 100.6 MHz). TLC: Silica gel PF₂₅₄

(Merck), 20×48 cm plates were employed using the solvents listed

below. Zones were detected by quenching of indicator fluorescence

upon exposure to 254 nm UV light. Column chromatography: silica

gel 7714 (Merck). Elemental analyses: Microanalysis Laboratory

of the Institute of Inorganic Chemistry, Technical University of

Braunschweig. MS: Finnigan MAT 8430 spectrometer at 70 eV.

IR: Perkin–Elmer 1420, Nicolet 320 FT-IR using KBr pellets and

paraffin films. UV: Beckman UV 5230. PC = 4-[2.2]paracyclo-

phanyl. 2,5-Dimethylstyrene (45) is a commercially available com-

pound (Aldrich); 1,4-dimethyl-2-propenylbenzene (46) has been re-

ported several times in the literature.^[37]We prepared it by Wittig

-4,-6,-11,-14) ppm. IR (KBr): ν = 3080 cm^–1(w), 2920 (s), 1620

˜

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A. A. Aly, S. Ehrhardt, H. Hopf, I. Dix, P. G. Jones

FULL PAPER

(m), 1585 (m), 1490 (m), 1480 (m), 980 (s), 930 (m), 900 (s), 860 ethano bridges), 5.12–5.18 (m, 2 H, =CH₂), 6.33–6.65 (m, 7 H, Ar-

(m), 790 (m). UV (methanol): λ_max(lg ε) = 218 nm (4.25), 281

(3.74), 232 (2.69). MS (70 eV): m/z (%) = 234 (71) [M⁺], 202 (12),

189 (13), 165 (13), 152 (16), 141 (12), 129 (100), 115 (76), 104 (74),

H) ppm. ¹³C NMR: δ = 23.86 (q, CH₃), 34.40, 35.15, 35.22, 35.42

(t, C-1,-2,-9,-10), 115.30 (t, =CH₂), 130.10, 130.62, 132.13, 132.19,

132.32, 132.94, 135.40 (d, C-5,-7,-8,-12,-13,-15,-16), 136.73, 139.18,

89 (41), 78 (56), 63 (42). C₁₈H₁₈(234.34): calcd. C 92.26, H 7.74; 139.29, 139.66, 142.95, 145.37 (s, C-3,-4,-6,-11,-14, Ar-C=) ppm.

found C 92.31, H 7.96.

IR (KBr): ν = 3080 cm^–1(w), 3025 (w), 2950 (m), 2920 (s), 2850

˜

(m), 1625 (m), 1590 (m), 1500 (m), 940 (m), 900 (s), 850 (s), 825

(m), 715 (s). UV (acetonitrile): λ_max(lg ε) = 215 nm (4.25), 225

(4.22), 263(3.53). MS (70 eV): m/z (%) = 248 (23) [M⁺], 143 (100),

129 (43), 127 (22), 105 (20). C₁₉H₂₀(248.37): calcd. C 91.88, H

8.12; found C 91.80, H 8.22.

b) 4-(1-Propenyl)[2.2]paracyclophane (16 and 17): To a suspension

of ethyl(triphenyl)phoshonium bromide (23.4 g, 63.0 mmol) in

200 mL of anhydrous tetrahydrofuran was added at 0 °C n-butyl-

lithium (33.2 mL, 63.0 mmol) in n-hexane (1.9 m). After stirring at

room temp. for 2 h a solution of 14 (10 g, 42.2 mmol) in 150 mL

of tetrahydrofuran was added to the ylid solution. The reaction

mixture was stirred at room temp. overnight and worked up as

described above for 7. After silica gel plate chromatography with

dichloromethane, 9.42 g (90%) of a colorless amorphous solid was

obtained. The diasteromeric mixture of 16 and 17 was separated by

HPLC (silica gel, n-hexane). The 16/17-isomer ratio varied strongly

between 1:1 and 6:1, depending on the quality of the butyllithium

solution.

d) 4-(2-Butenyl)[2.2]paracyclophane (19–21): To a solution of ethyl-

magnesium bromide [from magnesium (0.52 g, 21.4 mmol) and

ethyl bromide (1.6 mL, 21.4 mmol)] in 10 mL of anhydrous ether

was added at room temp. 15 (3.5 g, 14.0 mmol) in 150 mL of ether.

After heating the reaction mixture for 2 h under reflux it was

worked-up as described above. The isolated tertiary alcohol (2.7 g,

53%) was dissolved in 50 mL of trichloromethane, and 50 mL of

6 n hydrochloric acid was added. After vigorous stirring for 16 h

at room temp. the dehydration mixture was worked-up as described

above for 18: 2.90 g (79%) of a mixture of 19–21. HPLC separation

(silica gel, n-hexane) provided two fractions in 1:3 ratio.

Fraction 1: 17 (cis-isomer): Colorless needles (n-hexane), m.p.

1

4

3

111 °C. H NMR: δ = 1.67 (dd, J = 1.7, J = 7.0 Hz, 3 H, CH₃),

2.72–3.35 (m, 8 H, ethano bridges), 5.72 (dt, J_cis= 11.5, ³J =

7.0 Hz, 1 H, =CH–CH₃), 6.24–6.68 (m, 8 H, Ar-H and Ar-CH=)

ppm. ¹³C NMR: δ = 14.95 (q, CH₃), 33.87, 34.51, 35.21, 35.46 (t,

C-1,-2,-9,-10), 126.35, 129.34, 129.79, 131.30, 132.18, 132.98,

133.05, 134.49, 134.74 (d, C-5,-7,-8,-12,-13,-15,-16, -CH=CH-),

136.77, 138.15, 139.11, 139.25, 139.57 (s, C-3,-4,-6,-11,-14) ppm.

1

Fraction 1 19 + 21: H NMR: δ = 1.00 (t, J = 7.4 Hz, 3 H, CH₃of

ethyl group), 2.10–2.55 (br. q, 2 H, CH₂of ethyl group), 2.60–3.64

(m, 8 H, ethano bridges), 5.16 (br. s, 2 H, =CH₂), 5.8–6.9 (m, 7 H,

Ar-H); 21 was only present as a trace component.

Fraction 2, 20: Colorless needles (n-hexane), m.p. 95 °C. ¹H NMR:

δ = 1.81–1.83 (m, 3 H, =CHCH₃), 1.96 [br. s, 3 H, Ar-C(CH₃)=],

2.87–3.27 (m, 8 H, ethano bridges), 5.65–5.69 (m, 1 H, =CH), 6.31–

6.63 (m, 7 H, Ar-H) ppm. ¹³C NMR: δ = 14.37 (q, =CHCH₃),

18.02 [q, Ar-C(CH₃)=], 34.43, 35.19, 35.24, 35.46 (t, C-1,-2,-9,-10),

124.75, 129.94, 130.33, 131.53, 132.13, 132.26, 132.92, 135.29 (d, C-

5,-7,-8,-12,-13,-15,-16, =CH–CH₃), 136.68, 136.87, 139.05, 139.25,

IR (KBr): ν = 3053 cm^–1(m) cm^–1, 3020 (m), 2935 (s), 2860 (m),

˜

1645 (w), 1590 (m), 1560 (m), 1500 (s), 1440 (s), 940 (s), 910 (s),

870 (s), 800 (s), 770 (s), 750 (m), 720 (s). UV (acetonitrile): λ_max(lg

ε) = 215 nm (4.27), 222 (4.23), 276 (3.67), 311 (2.60). C₁₉H₂₀

(248.37): calcd. C 91.88, H 8.12; found C 91.80, H. 8.10.

Fraction 2: 16 (trans-isomer): Colorless needles (n-hexane), m.p.

106–108 °C. ¹H NMR: δ = 1.93 (dd, ⁴J = 1.7, ³J = 6.6 Hz, 3 H,

CH₃), 2.68–3.47 (m, 8 H, ethano bridges), 5.96 (dt, J_trans= 15.6, ³J

= 6.6 Hz, 1 H, =CH–CH₃), 6.34–6.69 (m, 8 H, Ar-H and Ar-CH=)

ppm. ¹³C NMR: δ = 18.8 (q, CH₃), 33.74, 34.65, 36.24, 35.49 (t, C-

1,-2,-9,-10), 126.22, 129.47, 129.56, 130.95, 130.98, 131.80, 132.94,

132.98, 134.66 (d,-5,-7,-8,-12,-13,-15,-16, Ar-CH, =CH–CH₃),

137.04, 138.01, 139.26, 139.35, 139.60 (s, C-3,-4,-6,-11,-14) ppm.

139.71, 145.18 (s, C-3,-4,-6,-11,-14, Ar-C=) ppm. IR (KBr): ν =

˜

3040 cm^–1(w), 2935 (s), 2860 (s), 1590 (m), 1510 (m), 1440 (m),

1420 (w), 1380 (m), 945 (m), 905 (s), 840 (s), 825 (m), 725 (s), 710

(m), 660 (s). UV (acetonitrile): λ_max(lg ε) = 216 nm (4.28), 222

(4.26), 265 (3.61). MS (70 eV): m/z (%) = 262 (81) [M⁺], 202 (10),

157 (100), 143 (93), 128 (78), 115 (41), 104 (57), 91 (36), 78 (41).

C₂₀H₂₂(262.40): calcd. C 91.55, H 8.45; found C 91.51, H 8.64.

IR (KBr): ν = 3040 cm^–1(w), 2940 (s), 2860 (m), 1595 (m), 1560

˜

2. Cycloadditions

(m), 1440 (s), 1420 (m), 965 (s), 945 (m), 900 (m), 800 (s), 720 (s).

UV (acetonitrile): λ_max(lg ε) = 218 nm (4.28), 282 (3.79), 317 (2.88).

MS (70 eV): m/z (%) = 248 (43) [M⁺], 143 (100), 141 (30), 129 (99),

115 (46), 104 (59), 91 (24), 84 (42), 78 (40). C₁₉H₂₀(248.37): calcd.

C 91.88, H 8.12; found C 91.87, H 8.12.

a) Maleic Anhydride (10a) to 7: In 100 mL of glacial acetic acid 7

(1.0 g, 4.3 mmol) and 10a (0.42 g, 4.3 mmol) were heated under

reflux for 5 d. The reaction mixture was cooled to room temp. al-

lowing the anhydride 24 to precipitate. A further crop of adduct

was obtained when the solution was concentrated to ca. 1/3 of its

volume; total yield: 1.03 g (72%) of 24, yellowish needles (acetic

acid), m.p. 263–265 °C. ¹H NMR (CF₃COOH; the adduct is insol-

uble in other solvents): δ = 1.57–1.67 (m, 1 H, 18-H), 2.31–2.41

(m, 2 H, 17-H), 2.27–3.70 (m, 10 H, 18-, 19-H, ethano bridges),

c) 4-(2-Propenyl)[2.2]paracyclophane (18): Methylmagnesium iodide

was prepared from magnesium (1.46 g, 60.0 mmol) and methyl io-

dide (3.73 mL, 60.0 mmol) in 45 mL of anhydrous ether. To this

solution was added 4-acetyl[2.2]paracyclophane (15)^[14](10.0 g,

40.0 mmol) in 500 mL of ether. The reaction mixture was stirred

under reflux for 2 h, cooled to room temp. and worked-up as de-

scribed above. The resulting tertiary alcohol (7.13 g, 67%) was used

as obtained in the dehydration step. To a solution of the tertiary

alcohol (10.62 g, 40.0 mmol) in 100 mL of trichloromethane was

added 70 mL of 6 n hydrochloric acid. After vigorous stirring at

room temp. for 12 h, the organic phase was separated, and the

aqueous phase carefully extracted with trichloromethane. The com-

bined organic phases were neutralized (hydrogen carbonate), dried

(sodium sulfate), and the solvent was removed in vacuo: 8.23 g

(83%) of 18, colorless plates (sublimed at 61 °C, 0.01 Torr), m.p.

3

4.04 (d, J = 8.4 Hz, 1 H, 20-H), 6.39 (dd, J = 7.9 and 1.8 Hz, 1

H, 12-H), 6.49–6.66 (m, 5 H, remaining Ar-H) ppm. Since the an-

hydride is unstable in trifluoroacetic acid, no ¹³C NMR spectrum

could be obtained. IR (KBr): ν = 3000 cm^–1(w), 2940 (s), 1860

˜

(m), 1780 (s), 1500 (m), 1470 (m), 1440 (m), 1415 (m), 1310 (m),

1225 (s), 1070 (s), 960 (s), 920 (s), 720 (s). UV (methanol): λ_max(lg

ε) = 227 nm (4.20). MS (70 eV): m/z (%) = 332 (26) [M⁺], 228 (30),

198 (10), 156 (18), 105 (15), 104 (100). C₂₂H₂₀O₃(332.40): calcd. C

79.50, H 6.06; found C 79. 47, H 6.04.

b) Maleic Anhydride (10a) to 16: In 250 mL of acetic acid com-

75 °C. ¹H NMR: δ = 2.04 (br. s, 3 H, CH₃), 2.87–3.37 (m, 8 H, pound 16 (2.4 g, 96.0 mmol) and 10a (1.12 g, 96.0 mmol) were

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Cycloadditions to Alkenyl[2.2]paracyclophanes

FULL PAPER

heated to reflux for 6 d. The solvent was removed in vacuo and the

residue taken up in ether; the adduct 25 (1.80 g, 54%) precipitated

as a yellowish solid. Recrystallization from ethanol provided ana-

lytically pure adduct, colorless needles, m.p. 179–181 °C. ¹H NMR:

H), 2.76–3.31 (m, 10 H, ethano bridges, 17-,18-H), 3.80 (s, 3 H,

COOCH₃), 3.82 (s, 3 H, COOCH₃), 6.38 and 6.43 (AB-q, ³J =

7.7 Hz, 2 H, 7-,8-H), 6.46–6.57 (m, 4 H, 12-,13-,15-,16-H) ppm.

¹³C NMR: δ = 20.70 (q, CH₃), 28.07 (d, C-17), 30.57, 32.18, 34.43,

34.84, 34.93 (t, C-1,-2,-9,-10,-18), 52.07 (q, COOCH₃), 52.25 (q,

COOCH₃), 127.45, 129.98, 131.03, 131.22, 132.21, 135.31 (d, C-7,-

3

δ = 1.00 (d, J = 6.5 Hz, 3 H, CH₃), 2.38–3.23 and 4.03–4.20 (m,

3

12 H, ethano bridges, 17-,18-,19-H), 3.87 (d, J = 6.1 Hz, 1 H, 20-

H), 6.41–6.60 (m, 6 H, Ar-H) ppm. ¹³C NMR: δ = 17.82 (q, CH₃), 8,-12,-13,-15,-16), 133.27, 134.18, 136.15, 136.48, 139.24, 139.31,

28.34 (d, C-18), 32.38, 33.32, 33.44, 33.78, 34.00 (t, C-1,-2,-9,-10,-

17), 45.31, 46.02 (d, C-19,-20), 127.24, 127.92, 132.07, 133.34,

133.48, 133.59 (d, C-7,-8,-12,-13,-15,-16), 129.60, 134.86, 138.32,

138.76, 139.16, 139.18 (s, C-3,-4,-5,-6,-11,-14), 172.19, 177.73 (s,

139.36, 141.22 (s, C-3,-4,-5,-6,-11,-14,-19,-20), 168.52 and 169.58 (s,

ester carbonyl groups) ppm. IR (KBr): ν = 3040 cm^–1(w), 2960 (s),

˜

2880 (m), 1750 (s), 1725 (s), 1630 (m), 1575 (m), 1460 (s), 1440 (s),

1310 (s), 1265 (s), 1230 (s), 1125 (s), 1080 (s), 1040 (m), 985 (m),

2×C=O) ppm. IR (KBr): ν = 2950 cm^–1(m), 1750 (s), 1700 (s), 880 (m), 800 (m), 780 (m). UV (methanol): λ_max(lg ε) = 213 nm

˜

1460 (m), 1450 (m), 1300 (s), 1210 (m), 1170 (s), 1150 (s), 1050 (m), (4.22), 222 (4.20), 245 (3.86), 330 (3.84). MS (70 eV): m/z (%) = 390

720 (m). UV (methanol): λ_max(lg ε) = 228 nm (4.15). MS (70 eV):

(7) [M⁺], 375 (14), 121 (12), 119 (15), 90 (28), 88 (92), 84 (100), 49

m/z (%) = 346 (30) [M⁺], 318 (41), 242 (88), 212 (84), 199 (29), 169 (25). C₂₅H₂₆O₄(390.48): calcd. C 76.90, H 6.71; found C 76.20, H

(77), 150 (78), 141 (35), 129 (40), 115 (37), 104 (100), 78 (40).

C₂₃H₂₂O₃(346.42): calcd. C 79.74, H 6.40; found 79.60, H 6.38.

6.73.

f) Diethyl Azodicarboxylate (10c) to 7: A mixture of 7 (1.00 g,

4.3 mmol), 10c (0.67 mL, 4.3 mmol), and trichloroacetic acid

(0.1 g, 6.0 mmol) in 100 mL of toluene was kept at room temp. for

7 d. After washing with water and drying with magnesium sulfate,

the solvent was removed in vacuo and the remaining oil separated

by plate chromatography (silica gel, dichloromethane): 0.26 g

(19%) of 27, colorless prisms (ether), m.p. 185–187 °C; 0.21 g of 7

were recovered unchanged. ¹H NMR: δ = 1.30–1.39 (overlapping

q, 6 H, 2×CH₃), 2.90–3.54 (m, 10 H, ethano bridges and 18-H),

4.17–4.35 (m, 4 H, –OCH₂–), 5.18 (dd, J = 9.1 and 2.6 Hz, 1 H, 17-

H), 6.32–6.56 (m, 7 H, 5-,7-,8-,12-,13-,15-,16-H) ppm. ¹³C NMR: δ

= 14.22 (q, CH₃), 14.72 (q, CH₃), 33.67, 34.88, 35.02, 35.21 (t, C-

1,-2,-9,-10), 43.09 (t, C-18), 62.28 (t, –OCH₂–), 64.29 (t, –OCH₂–),

76.24 (d, C-17), 130.64, 130.75, 132.08, 133.04, 133.27, 134.17,

136.25 (d, C-5,-7,-8,-12,-13,-15,-16), 132.82, 139.14, 139.32, 139.56,

140.33 (s, C-3,-4,-6,-11,-14) ppm; the signals for C-19 (line broad-

ening, possibly because of rotation about the urethane C–N bond

at intermediate rate) and the ester carbonyl group could not be

c) Dimethyl Acetylenedicarboxylate (10b) to 7: A solution of com-

pound 7 (8.0 g, 34.4 mmol) and 10b (4.2 mL, 34.4 mmol) in 750 mL

of glacial acetic acid was refluxed for 3 d. The solvent was removed

in vacuo and the oily residue purified by thick layer chromatog-

raphy (silica gel, dichloromethane): 9.2 g (72%) of diester 26a, col-

orless prisms (ether/ethanol), m.p. 129–131 °C. ¹H NMR: δ = 2.33–

3.43 (m, 12 H, ethano bridges, 17-,18-H), 3.79 (s, 3 H, COOCH₃),

3

3.88 (s, 3 H, COOCH₃), 6.37 and 6.41 (AB-q, 2 H, J = 7.8 Hz, 7-

,8-H), 6.52–6.62 (m, 4 H, 12-,13-,15-,16-H) ppm. ¹³C NMR: δ =

23.12 (t, C-18), 24.08 (t, C-17), 32.50, 34.39, 34.82, 35.09 (t, C-1,-

2,-9,-10), 51.99 and 52.24 (q, COOCH₃), 130.04, 131.34, 132.39,

132.90, 134.34, 135.97 (d, C-7,-8,-12,-13,-15,-16), 128.87, 130.96,

136.10, 136.63, 138.26, 138.82, 139.22, 139.28 (s, C-3,-4,-5,-6,-11,-

14,-19,-20), 167.76 and 169.98 (s, ester carbonyl groups) ppm. IR

(KBr): ν = 3030 cm^–1(w), 2950 (m), 2920 (m), 2850 (m), 1730 (s),

˜

1715 (s), 1610 (m), 1265 (s), 1225 (s), 1205 (s), 1110 (m), 790 (m).

UV (methanol): λ_max(lg ε) = 222 nm (4.24), 329 (3.91). MS (70 eV):

m/z (%) = 376 (80) [M⁺], 345 (20), 317 (39), 272 (100), 257 (95),

239 (82), 227 (38), 213 (90), 183 (61), 153 (65). C₂₄H₂₄O₄(376.45):

calcd. C 76.57, H 6.43; found C 76.89, H 6.62.

observed. IR (KBr): ν = 3450 cm^–1(br., w), 3000 (m), 2930 (m),

˜

1700 (s), 1665 (s), 1495 (m), 1450 (s), 1390 (m), 1380 (s), 1355 (m),

1300 (s), 1040 (m), 1000 (m), 900 (m), 875 (m). UV (methanol):

λ_max(lg ε) = 225 nm (4.32), 285 (2.83). MS (70 eV): m/z (%) = 408

(14) [M⁺], 231 (13), 143 (24), 129 (100), 115 (31), 104 (86), 86 (74),

84 (86), 78 (21). C₂₄H₂₈N₂O₄(408.50): calcd. C 70.57, H 6.91, N

6.86; found C 70.46, H 7.00, N 6.63.

d) Dimethyl Acetylenedicarboxylate (10b) to 16: As described for 7,

compound 16 (6.09 g, 24.4 mmol) and 10b (3.02 mL, 24.6 mmol)

were reacted in 750 mL of acetic acid for 5 d to yield 3.91 g (41%)

1

of 26b, colorless prisms (ethanol), m.p. 152–154 °C. H NMR: δ =

g) Diethyl Azodicarboxylate (10c) to 18: A solution of 18 (1.0 g,

4.0 mmol), trichloroacetic acid (0.1 g, 6.0 mmol) and 10c (0.63 mL,

4.0 mmol) in 100 mL of toluene was kept at room temp. for 7 d.

Work-up as described above for 7 provided 0.34 g (30%) of 28,

while 0.31 g of 18 was revovered; white-yellow prisms (ethanol),

m.p. 120–122 °C. ¹H NMR: δ = 1.20–1.25 (overlapping q, 6 H,

2×CH₃), 2.92–3.06 (m, 8 H, ethano bridges and –NCH₂–), 4.10–

4.19 (m, 6 H, 2×–OCH₂– and ethano bridges), 5.30 and 5.40 (m,

2 H, =CH₂), 6.34–6.65 (m, 8 H, Ar-H, –NH) ppm. ¹³C NMR: δ =

15.40 (q, 2×CH₃), 34.10, 35.04, 35.25, 35.31 (t, C-1,-2,-9,-10),

55.90 (br. t, –NCH₂–), 61.90 (t, –OCH₂–), 62.45 (t, –OCH₂–),

115.73 (br. t, =CH₂), 129.59 (2×), 131.33, 132.10, 132.28, 133.05,

135.24 (d, C-5,-7,-8,-12,-13,-15,-16), 138.94, 139.34, 139.47, 139.56

(2×), 145.31 (s, C-3,-4,-6,-11,-14,-7) ppm; the C=O signals were not

3

0.88 (d, J = 6.9 Hz, 3 H, CH₃), 2.53–3.22 (m, 11 H, ethano brid-

ges, 17-,18-H), 3.80 (s, 3 H, COOCH₃), 3.92 (s, 3 H, COOCH₃),

3

6.38 and 6.42 (AB-q, J = 7.8 Hz, 2 H, 7-,8-H), 6.55–6.64 (m, 4 H,

12-,13-,15-,16-H) ppm. ¹³C NMR: δ = 16.95 (q, CH₃), 27.58 (d, C-

18), 32.39, 32.63, 34.22, 34.56, 35.01 (t, C-1,-2,-9,-10,-17), 51.99

(q, COOCH₃), 52.33 (q, COOCH₃), 128.57, 132.32, 132.63, 134.02,

135.01, 136.75 (d, C-7,-8,-12,-13,-15,-16), 129.44, 131.32, 134.24,

135.98, 137.93, 138.15, 139.19, 139.23 (s, C-3,-4,-5,-6,-11,-14,-19,-

20), 167.43 and 170.44 (s, ester carbonyl groups) ppm. IR (KBr):

ν = 2990 cm^–1(m), 2890 (m), 2950 (m), 1730 (s), 1720 (s), 1600

˜

(m), 1440 (s), 1310 (s), 1290 (s), 1285 (s), 1255 (s), 1080 (s), 1030

(m), 960 (m), 880 (m), 825 (m), 750 (m). UV (methanol): λ_max(lg

ε) = 212 nm (4.22), 223 (4.23), 256 (3.92), 3.29 (3.96). MS (70 eV):

m/z (%) = 390 (77) [M⁺], 331 (16), 286 (100), 271 (89), 253 (47),

227 (63), 195 (83), 186 (36), 104 (70), 78 (18), 59 (35). C₂₅H₂₆O₄

(390.48): calcd. C 76.90, H 6.71; found C 76.96, H 6.88.

observed. IR (KBr): ν = 3260 cm^–1(s), 3000 (m), 2950 (m), 1770

˜

(s), 1535 (s), 1495 (m), 1480 (m), 1450 (s), 1390 (m), 1295 (s), 1270

(s), 1225 (br., s), 1080 (s), 915 (m), 800 (m), 790 (m). UV (meth-

anol): λ_max(lg ε) = 215 nm (4.25), 223 (4.24). MS (70 eV): m/z (%)

= 422 (17) [M⁺], 349 (16), 320 (18), 262 (37), 246 (58), 228 (64),

200 (21), 184 (21), 157 (72), 141 (100), 128 (72), 105 (68), 104 (68),

91 (24). C₂₅H₃₀N₂O₄(422.52): calcd. C 71.07, H 7.16, N 6.63;

found C 71.03, H 7.19, N 6.56.

e) Dimethyl Acetylenedicarboxylate (10b) to 18: As described for 7,

compound 18 (7.0 g, 28.0 mmol) and 10b (3.44 mL, 28.0 mmol)

were reacted in 700 mL of acetic acid for 5 d to yield 5.57 g (51%)

of 26c, colorless needles (ether/ethanol), m.p. 135–137 °C. ¹H

NMR: δ = 0.92 (d, ³J = 7.2 Hz, 3 H, CH₃), 2.46 (m, 1 H, 18-

Eur. J. Org. Chem. 2006, 335–350

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345

A. A. Aly, S. Ehrhardt, H. Hopf, I. Dix, P. G. Jones

FULL PAPER

h) 1-Phenyl-1,3,4-triazolin-2,4-dione (10d) to 7: A solution of 7

(1.00 g, 4.3 mmol), 10d (0.75 g, 4.3 mmol) and trichloroacetic acid

(100 mg, 6.0 mmol) in 100 mL of toluene was kept at room temp.

for 7 d. The reaction mixture was washed with water, dried with

magnesium sulfate, and the solvent was removed in vacuo. When

the oily residue was taken up in ethanol, the 2:1 adduct 34 precipi-

tated as a colorless, amorphous solid (0.81 g, 32%), m.p. 214–

216 °C. ¹H NMR: δ = 1.56–1.67, 2.27–2.62, 2.81–3.20 (m, 8 H,

ethano bridges), 4.26 (dd, J = 18.1 and 4.7 Hz, 1 H, 18-H), 4.67

(dd, J = 18.1 and 2.2 Hz, 1 H, 18-H), 4.90 (d, J = 2.2 Hz, 1 H, 8-

H), 5.51 (dt, J = 6.3 and 2.2 Hz, 1 H, 5-H), 5.96 (d, J = 6.3 Hz, 1

k) Tetracyanoethene (10e) to 20: From compound 20 (0.7 g,

2.7 mmol) and 10e (0.35 g, 2.7 mmol) in 55 mL of acetic acid under

the above conditions was obtained 42 (0.47 g, 44%) as a mixture

1

of diastereomers; colorless needles (ethanol), m.p. 173–175 °C. H

NMR: δ = 1.66 (d, ³J = 7.0 Hz, 3 H, CH₃, H-22), 1.76 (d, ³J =

6.9 Hz, 3 H, CH₃, H-22), 2.16 and 2.17 (2×s, 3 H, CH₃, H-21),

3

2.78–3.38 (m, 8 H, ethano bridges), 3.79 (q, J = 6.9 Hz, 1 H, 18-

H), 6.05–6.74 (m, 7 H, H-5,-7,-8,-12,-13,-15,-16) ppm. ¹³C NMR:

δ = 13.12 and 13.70 (q, CH₃), 22.05 (q, CH₃), 33.84, 34.57, 34.96,

35.11 (2×), 35.22, 35.71, 35.89 (t, C-1,-2,-9,-10), 38.56 (s, C-17),

46.56 and 47.67 (d, C-18), 54.37, 55.32 (s, C-19,-20), 110.28, 110.36

H, 6-H), 6.22 (dd, J = 4.7 and 2.2 Hz, 1 H, 17-H), 6.84 and 6.99 (s, CN), 126.23, 127.77, 131.22, 131.56, 131.76, 131.87, 132.73,

(AB-q, J = 7.8 Hz, 2 H, 15-,16-H), 7.12–7.56 (m, 12 H, 2×C₆H₅, 132.90, 134.48, 134.58, 137.18, 137.27 (d, C-5,-7,-8,-12,-13,-15,-16),

12-,13-H) ppm. ¹³C NMR: δ = 31.95, 33.86, 37.91, 43.88 (t, C-1, 135.97, 138.05, 138.33, 139.82, 139.97, 140.09, 140.87, 141.03 (s, C-

-2,-9,-10), 44.03 (t, C-18), 58.78 (d, C-5), 60.14 (d, C-6), 65.01 (s, C-

3,-4,-6,-11,-14) ppm. IR (KBr): ν = 3060 cm^–1(w), 2980 (m), 2920

˜

3), 123.47, 123.74, 125.21 (2×), 125.42 (2×), 126.62, 128.24, 128.28, (s), 2850 (m), 2250 (w), 1590 (m), 1460 (s), 1410 (m), 1400 (m),

129.07 (2×), 129.09 (2×), 130.35, 130.74, 135.24 (d, C-10,-12,-13, 1120 (m), 900 (m), 880 (m), 800 (m), 720 (s). UV (methanol): λ_max

-15,-16,-17, 2×C₆H₅), 131.25 (2×), 136.61, 137.84, 141.35, 141.66

(s, C-4,-7,-11,-14, 2×N–Ph), 151.63, 151.95, 155.60, 156.15 (s,

(lg ε) = 227 nm (4.26). MS (70 eV): m/z (%) = 390 (10) [M⁺], 158

(27), 157 (100), 143 (49), 128 (39), 105 (16), 104 (74). C₂₆H₂₂N₄

4×C=O) ppm. IR (KBr): ν = 3080 cm^–1(w), 2920 (m), 1770 (m), (390.49): calcd. C 79.97, H 5.68, N 14.35; C 79.88, H 5.85, N 14.27.

˜

1720 (s), 1620 (m), 1600 (m), 1500 (s), 1410 (s), 900 (w), 760 (m),

l) Tetrachloro-o-quinone (10f) to 2-Vinyl-p-xylene (45): To a re-

720 (m), 690 (m). UV (methanol): λ_max(lg ε) = 224 nm (4.49), 300

fluxing solution of 45 (0.27 g, 2 mmol) in dry toluene (30 mL), a

(3.45). MS (70 eV): m/z (%) = 584 (10) [M⁺], 409 (19), 290 (9), 178

solution of 10f (0.49 g, 2 mmol) in dry toluene (20 mL) was added

dropwise under N₂during 30 min; the mixture was refluxed for 3 d.

(8), 177 (50), 129 (14), 120 (24), 119 (100), 92 (12), 91 (53), 77 (18).

C₃₄H₂₈N₆O₄(584.63): calcd. C 69.85, H 4.83, N 14.38; found C

The solvent was concentrated in vacuo and the residue was sepa-

69.70, H 4.78, N 14.20.

rated by plate chromatography (silica gel, cyclohexane) to give ad-

i) Tetracyanoethene (10e) to 7: A solution of 7 (0.8 g, 3.4 mmol) 10e

(0.435 g, 3.4 mmol) in 60 mL of glacial acetic acid was kept at room

temp. for 3 d. When the solvent was removed in vacuo the [2+2]

adduct 37 or 39 precipitated (0.41 g, 33%) as a violet solid;

recrystallization from ethanol provided colorless needles (m.p. 193–

duct 47 (0.43 g, 56%) as colorless crystals (cyclohexane), m.p.

163 °C. H NMR: δ = 2.36 (s, 6 H, 2 CH₃), 4.02 (dd, J = 11.8 and

1

9.0 Hz, 1 H, 3-H), 4.52 (dd, J = 11.8 and 2.3 Hz, 1 H, 3-HЈ), 5.34

(dd, J = 8.9 and 2.3 Hz, 1 H, 2-H), 7.12–7.14 (m, 2 H, Ar-H), 7.35

(s, 1 H, Ar-H) ppm. ¹³C NMR: δ = 18.55, 21.08 (q, 2×CH₃), 68.53

(C-3), 73.09 (C-2), 120.36, 120.88 (Ar-C-Cl, C-6 and/or C-9),

124.61, 124.71 (Ar-C-Cl, C-7 and/or C-8), 126.72 (Ar-C), 128.28,

129.83, 130.77 (Ar-CH), 132.14, 132.16 (Ar-C), 139.36 (C-5),

1

196 °C) which soon turned yellow. H NMR: δ = 2.99–3.50 (m, 10

H, ethano bridges and 18-H), 4.59 (dd, J = 12.1 and 8.4 Hz, 1 H,

17-H), 6.18 (br. s, 1 H, H-5), 6.26–6.68 (m, 6 H, 7-,8-,12-,13-,15-,

16-H) ppm. ¹³C NMR: δ = 33.62, 34.51, 34.95, 35.23 (2×) (t, C-1,

-2,-9,-10, C-18), 43.88 (2×) (s, C-19,-20), 45.69 (d, C-17), 108.03,

109.84, 110.39, 111.09 (s, 4×CN), 129.54, 131.53, 132.03, 133.57,

133.87, 134.97, 136.57 (d, C-5,-7,-8,-12,-13,-15,-16), 130.73, 137.91,

139.63 (Ar-C-10) ppm. IR (KBr): ν = 3020–3000 cm^–1(w), 2949–

˜

2865 (w), 1590 (s), 1438 (m), 1380 (s), 1554 (s), 1380 (m), 1330 (w),

1280 (m), 1080 (s). MS (70 eV): m/z (%) = 382 [M⁺+ 4] (20), 380

[M⁺+ 2] (36), 378 [M⁺] (100), 376 (82), 261 (12), 259 (30), 132

(40), 117 (52), 115 (22). C₁₆H₁₂Cl₄O₂(378.09): calcd. C 50.83, H

3.20, Cl 37.51; found C 50.70, H 3.16, Cl 37.44.

138.81, 139.88, 141.64 (s, C-3,-4,-6,-11,-14). IR (KBr):

ν =

˜

3020 cm^–1(w), 2960 (s), 2940 (s), 2860 (m), 1595 (s), 1500 (s), 1490

(m), 1440 (m), 960 (m), 940 (m), 900 (s), 850 (m). UV (methanol):

λ_max(lg ε) = 227 nm (4.28). MS (70 eV): m/z (%) = 362 (5) [M⁺],

335 (2), 192 (6), 130 (12), 129 (23), 105 (23), 104 (100), 78 (11).

C₂₄H₁₈N₄(362.43): calcd. C 79.54, H 5.00, N 15.46; found C 79.

70, H 4.93, N 15.67.

m) Tetrachloro-o-quinone (10f) to 2-(E-1-Propenyl)-p-xylene (46):

As described for 45, a solution of 46 (0.29 g, 2 mmol) and 10f

(0.49 g, 2 mmol) in anhydrous toluene (50 mL) was refluxed under

N₂for 3 d. The solvent was removed in vacuo and the residue was

separated by plate chromatography (silica gel, cyclohexane) to give

48 (0.46 g, 65%), as colorless crystals (cyclohexane), m.p. 120–

122 °C. ¹H NMR: δ = 1.00 (d, J = 6.3 Hz, 3 H, CH₃), 2.17 (s, 6 H,

2×CH₃), 4.12–4.18 (m, 1 H, 3-H), 4.52 (d, J = 8.00 Hz, 1 H, 2-H),

6.36–7.35 (m, 3 H, Ar-H) ppm. ¹³C NMR: δ = 15.87 (CH₃), 25.08,

25.23 (2 CH₃, p-xylene), 67.69 (C-3), 76.65 (C-2), 122.60, 124.61

(Ar-C-Cl, C-6 and/or C-8), 131.00, 132.40 (Ar-C-Cl, C-7 and/or C-

8), 132.48, 132.71, 134.56 (Ar-CH), 135.87, 136.40 (Ar-C), 139.56

j) Tetracyanoethene (10e) to 18: As described above for 7, a solution

of 18 (0.8 g, 3.2 mmol) and 10e (0.41 g, 3.2 mmol) in 60 mL of

acetic acid was kept at room temp. for 2 d. The adduct 41 crys-

tallized from the solution as colorless needles: 0.97 g (81%); m.p.

126 –128 °C. ¹H NMR: δ = 2.29 (s, 3 H, CH₃), 2.45–2.58 and 2.93–

3.27 (m, 8 H, ethano bridges), 3.30 and 3.47 (AB, J = 12.6 Hz, 2

H, 18-H), 6.26–6.49 and 6.67–6.76 (m, 7 H, 5-,7-,8-,12-,13-,15-,16-

H) ppm. ¹³C NMR: δ = 20.55 (q, CH₃), 32.87 (s, C-17), 33.45,

35.12, 35.23, 35.85, 44.27 (t, C-1,-2,-9,-10,-18), 51.55 (2×) (s, C-

19,-20), 108.68, 109.30, 110.35, 111.79 (s, 4×CN), 127.03, 131.17,

132.12, 132.40, 133.23, 135.04, 136.73 (d, C-5,-7,-8,-12,-13,-15,-16),

134.65, 138.16, 139.15, 140.07, 140.79 (s, C-3,-4,-6,-11,-14) ppm.

(p-xylene-C), 139.78 (C-5), 140.46 (C-10) ppm. IR (KBr): ν = 3025–

˜

3006 cm^–1(m), 2985–2855 (m), 1557 (s), 1060 (s). MS (70 eV):

m/z (%) = 396 [M⁺+ 4] (24), 394 [M⁺+ 2] (50), 392 [M⁺] (100),

390 (18), 349 (6), 275 (10), 273 (22), 271 (18), 147 (12), 146 (80),

131 (52), 105 (10), 91 (12). C₁₇H₁₄Cl₄O₂(392.12): calcd. C 52.07,

H 3.60, Cl 36.17; found C 51.90, H 3.54, Cl 36.00.

IR (KBr): ν = 3000 cm^–1(m), 2980 (m), 2920 (s), 2850 (m), 2250

˜

(w), 1900 (w), 1590 (m), 1450 (s), 1385 (s), 1300 (m), 1260 (m), 900

(s), 790 (s), 720 (s). UV (methanol): λ_max(lg ε) = 226 nm (4.21).

MS (70 eV): m/z (%) = 248 (58) [M⁺– 128 (TCNE)], 143 (100), 129

(62), 128 (62), 105 (20), 76 (16). C₂₅H₂₀N₄(376.46): calcd. C 79.76,

H 5.35, N 14.88; C 79.70, H 5.30, N 14.76.

n) Tetrachloro-o-quinone (10f) to 7: To a refluxing solution of 7

(0.47 g, 2.0 mmol) in anhydrous toluene (50 mL), a solution of 10f

(0.49 g, 2 mmol) in anhydrous toluene (50 mL) was added dropwise

under N₂during 30 min. After further refluxing for 2 d (the reac-

346

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Eur. J. Org. Chem. 2006, 335–350

Cycloadditions to Alkenyl[2.2]paracyclophanes

FULL PAPER

tion was monitored by TLC), the solvent was removed in vacuo

and the residue was subjected to plate chromatography (silica gel,

hexane): adduct 49 was obtained (0.60 g, 62%) as colorless needles

243 (12), 105 (20). C₃₄H₂₈O (452.60): calcd. C 90.23, H 6.23; found

C 90.10, H 6.20.

q) 2-Dicyanomethylenindane-1,3-dione (10h) to 7: A mixture of 7

(0.47 g, 2 mmol) and 10h (0.42 g, 2 mmol) in anhydrous toluene

(150 mL) was refluxed under N₂for 10 d. The toluene was evapo-

rated in vacuo and the residue was subjected to silica gel column

chromatography with benzene/hexane (1:1) to give 53 (0.82 g, 93%)

as yellow crystals (benzene/cyclohexane), m.p. 130–132 °C. ¹H

NMR: δ = 2.75 (dd, J = 15.2 and 11.6 Hz, 1 H, 18-H), 2.99–3.39

(m, 8 H, ethano bridges and 18-HЈ), 3.42–3.50 (m, 1 H, ethano

bridges), 5.42 (dd, J = 11.6 and 1.3 Hz, 1 H, 17-H), 6.42 (s, 1 H,

5-H), 6.46 (d, J = 7.6 Hz, 1 H, PC-H), 6.54–6.62 (m, 5 H, PC-H),

7.35 (dd, J = 8.7 and 1.8 Hz, 1 H, 27-H), 7.42–7.46 (m, 2 H, 25-,

26-H), 7.60 (dd, J = 8.8 and 2.0 Hz, 1 H, 24-H) ppm. ¹³C NMR:

δ = 25.90 (C-19), 32.80, 34.50, 35.30, 35.70 (t, C-1,-2,-9,-10), 36.50

(C-18), 78.65 (C-17), 97.68 (C-20), 115.66, 116.25 (2×CN), 126.50,

128.00, 128.65 (Ar-CH), 128.78, 129.40, 130.89 (PC-CH), 131.29

(Ar-CH), 131.68 (PC-C), 131.97, 132.25, 132.31, 132.98 (PC-CH),

133.14, 133.30, 133.58, 135.25 (PC-C), 135.77, 138.90 (Ar-C),

1

(cyclohexane), m.p. 210–212 °C. H NMR: δ = 2.80–3.20 (m, 6 H,

ethano bridges), 3.28–3.54 (m, 2 H, ethano bridges), 4.30 (dd, J =

11.9 and 8.9 Hz, 1 H, 18-H), 4.40 (dd, J = 11.9 and 2.3 Hz, 1 H,

18-HЈ), 5.03 (dd, J = 9.0 and 2.3 Hz, 1 H, 17-H), 6.38–6.54 (m, 5

H, H-PC), 6.58 (br., s, 1 H, 5-H), 6.88 (d, J = 8.0 Hz, 1 H, 8-H)

ppm. ¹³C NMR: δ = 28.00, 34.88, 35.01, 35.22 (t, C-1,-2,-9,-10),

67.69 (C-18), 77.28 (C-17), 120.10, 120.19 (Ar-C-Cl, C-21 and/or

C-24), 124.18, 124.50 (C-22 and/or C-23), 130.12, 132.31, 132.44,

132.58, 134.08, 134.38, 134.47 (PC-C), 134.72, 137.04, 138.44,

138.52 (PC-C), 139.99 (C-4), 141.50 (C-20), 142.16 (C-25) ppm. IR

(KBr): ν = 3010–3000 cm^–1(m), 2974–2951 (m), 1580 (s), 1556 (s),

˜

1390 (s), 1280 (m), 1095 (s). MS (70 eV): m/z (%) = 484 [M⁺+ 4]

(12), 482 [M⁺+ 2] (48), 480 [M⁺] (100), 478 (24), 447 (10), 445

(24), 443 (26), 223 (10), 149 (22), 129 (52), 104 (60), 84 (74), 51

(38), 49 (76). C₂₄H₁₈Cl₄O₂(480.209): calcd. C 60.03, H 3.78, Cl

29.53; found C 59.88, H 3.70, Cl 29.48.

175.95 (C-28), 187.23 (C-22) ppm. IR (KBr): ν = 3032–3010 cm^–1

˜

o) Tetrachloro-o-quinone (10f) to 16: From 16 (0.5 g, 2. 0 mmol) in

50 mL of toluene and 10f (0.49 g, 2 mmol) in toluene (50 mL, re-

flux for 2 d) adduct 50 (0.7 g, 71%) was obtained according to the

above procedure as colorless crystals (cyclohexane), m.p. 185 °C.

¹H NMR: δ = 0.88 (d, J = 6.4 Hz, 3 H, CH₃), 2.80–3.10 (m, 4 H,

ethano bridges), 3.18–3.30 (m, 2 H, ethano bridges), 3.35–3.55 (m,

(s), 2925–2853 (s), 2220 (w), 1711 (s), 1626 (s), 1586 (s), 1407 (s),

1306 (m), 1080 (s). MS (70 eV): m/z (%) = 442 [M⁺] (38), 415 (8),

311 (14), 310 (12), 284 (10), 130 (32), 129 (80), 105 (50), 104 (100),

78 (20). C₃₀H₂₂N₂O₂(442.52): calcd: C 81.43, H 5.01, N 6.37;

found C 81.30, H 5.00, N 6.30.

2 H, ethano bridges), 4.25–4.32 (m, 1 H, 18-H), 4.51 (d, J = 8.0 Hz, 3. Aromatization Reactions

1 H, 17-H), 6.43–6.55 (m, 5 H, PC-H), 6.58 (s, 1 H, 5-H), 7.11 (d,

a) of Anhydrides 24 and 25: A solution of 24 (0.30 g, 0.9 mmol) and

2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) (0.41 g,

J = 8.0 Hz, 1 H, 8-H) ppm. ¹³C NMR: δ = 17.07 (CH₃), 34.19,

35.00, 35.29, 35.38 (t, C-1,-2,-9,-10), 73.81 (C-18), 83.92 (C-17),

120.10, 120.35 (Ar-C-Cl, C-21 and/or C-24), 124.37, 124.62 (Ar-C-

Cl, C-22 and/or C-23), 130.58, 132.20, 132.29, 132.89, 134.15,

134.65, 134.81 (PC-CH), 137.32, 138.31, 139.62, 139.71 (PC-C),

1.8 mmol) in 100 mL of chlorobenzene was refluxed for 2 d. On

cooling to room temp., the hydroquinone precipitated. It was re-

moved by filtration and washed thoroughly with dichloromethane.

The solvent of the combined organic phases was removed in vacuo

and the resulting residue purified by plate chromatography (silica

gel, dichloromethane): 0.20 g (67%) of 54a, colorless prisms (meth-

140.08 (C-4), 140.28 (C-20), 140.34 (C-25) ppm. IR (KBr): ν =

˜

3015–3000 cm^–1(w), 2974–2851 (w), 1557 (s), 1508 (m), 1430 (vs),

1405 (s), 1378 (s), 1364 (m), 1337 (m), 1325 (m), 1073 (s), 970 (s).

MS (70 eV): m/z (%) = 499 [M⁺+ 4] (8), 497 [M⁺+ 3] (22), 496

[M⁺+ 2] (58), 494 [M⁺] (100), 492 (80), 460 (30), 459 (94), 456

(24), 390 (20), 389 (24), 317 (24), 247 (10), 231 (12), 145 (24), 143

(62), 129 (54), 104 (80), 91 (18), 78 (10). C₂₅H₂₀Cl₄O₂(494.26):

calcd. C 60.75, H 4.08, Cl 28.69; found C 60.65, H 4.00, Cl 28.55.

1

anol), m.p. 282 –283 °C. H NMR: δ = 2.75–3.31 (m, 6 H, ethano

bridges), 3.81–3.91 (m, 1 H, ethano bridge), 4.50–4.59 (m, 1 H,

ethano bridge), 5.50–5.60 (m, 2 H, 16-,17-H), 6.46–6.62 (m, 2 H,

19-,20-H), 7.00 and 7.08 (AB-q, J = 7.4 Hz, 2 H, 11-,12-H), 7.93

and 8.24 (AB-q, J = 8.4 Hz, 2 H, 5-,6-H) ppm. ¹³C NMR: δ =

33.74, 34.21, 34.95, 36.72 (t, C-1,-2,-13,-14), 119.01, 128.89, 130.00,

132.02, 132.22, 133.81, 135.05, 137.37 (d, C-5,-6,-11,-12,-16,-17,

-19,-20), 127.02, 130.05, 130.80, 137.84, 137.85, 138.17, 139.34,

140.62 (s, C-3,-4,-7,-8,-9,-10,-15,-18), 162.88 and 163.80 (s, car-

p) (E)-1,2-Dibenzoylethene (10g) to 7: A mixture of 7 (0.47 g,

2 mmol) and 10g (0.47 g, 2 mmol) in glacial acetic acid (50 mL)

and acetic anhydride (5 mL) was refluxed under N₂for 3 d. The

solid precipitate formed after cooling was collected by filtration

and washed several times by water and then with cyclohexane. Af-

ter drying in vacuo, compound 52 (0.82 g, 91%) was obtained as

bonyl groups) ppm. IR (KBr): ν = 2925 cm^–1(m), 1845 (m), 1770

˜

(s), 1570 (m), 1440 (m), 1285 (s), 1180 (s), 1160 (m), 920 (s), 880

(m), 740 (s). UV (methanol): λ_max(lg ε) = 213 nm (4.39), 275 (4.25),

303 (3.58), 351 (3.18). MS (70 eV): m/z (%) = 328 (87) [M⁺], 252

(12), 239 (14), 224 (46), 196 (31), 168 (18), 152 (42), 126 (24), 104

(100), 103 (63), 78 (56), 77 (36). C₂₂H₁₆O₃(328.37): calcd. C 80.47,

H 4.91; found C 80.84, H 4.91.

1

pale yellow crystals (acetonitrile), m.p. 262–264 °C. H NMR: δ =

2.41–2.61 (m, 2 H, ethano bridges), 2.63–2.95 (m, 3 H, ethano brid-

ges), 3.00–3.36 (m, 6 H, ethano bridges), 3.44–3.47 (m, 1 H, ethano

bridges), 6.26–6.35 (m, 3 H, 7-, 8-,13-H), 6.37 (dd, J = 8.0 and 1.2

Hz, 1 H, 12-H), 6.48 (dd, J = 8.9 and 1.8 Hz, 1 H, 15-H), 6.68 (dd, By the same procedure from 25 (0.50 g, 1.4 mmol) and DDQ

J = 8.4 and 1.4 Hz, 1 H, 16-H), 7.24–7.30 (m, 2 H, Ph-para-H),

7.40–7.58 (m, 2 H, Ph-meta-H), 7.68–7.80 (m, 2 H, Ph-ortho-H)

ppm. ¹³C NMR: δ = 20.09 (t, C-18), 26.40 (t, C-17), 33.49, 34.53,

(0.635 g, 2.8 mmol) was prepared 0.312 g (65%) of the methyl de-

rivative 54b, yellowish prisms (methanol), m.p. 273–275 °C. ¹H

NMR: δ = 2.87 (s, 3 H, CH₃), 2.74–3.29 (m, 6 H, ethano bridges),

34.92, 35.28 (t, C-1,-2,-9, and –10), 121.00 (s), 121.02 (s), 125.14, 3.78–3.85 (m, 1 H, ethano bridge), 4.44–4.54 (m, 1 H, ethano

125.35 (d each, Ph-H-ortho), 126.90, 127.56 (d each, Ph-H-para), bridge), 5.52–5.61 (m, 2 H, 16-,17-H), 6.57 (br. s, 2 H, 19-,20-H),

128.32, 128.72 (d, each, Ph-H-meta), 129.47 (s), 130.44 (d), 131.30

6.94 and 7.00 (AB-q, J = 7.4 Hz, 2 H, 11-,12-H), 7.95 (s, 1 H, 5-

(s), 131.38 (d), 132.23 (d), 132.46 (s), 133.40 (d), 133.42 (d), 134.28 H) ppm. ¹³C NMR: δ = 18.25 (q, CH₃), 33.58, 34.43, 34.96, 36.70

(d), 135.88 (s, 2 C), 137.22 (s, Ph-C), 139.05 (s, C-19), 140.26 (s, C-

21), 145.81 (s, C-20), 147.35 (s, C-22). IR (KBr): ν = 3047–

(t, C-1,-2,-13,-14), 122.45, 130.20, 131.92, 132.23, 134.52, 135.06,

136.47 (d, C-5,-11,-12,-16,-17,-19,-20), 127.54, 129.21, 132.76,

˜

3007 cm^–1(m), 2966–2849 (m), 1575 (m-s), 1050 (s). MS (70 eV): 137.01, 137.52, 137.87, 139.27, 140.77 (s, C-3,-4,-6,-7,-8,-9,-10,-15,

m/z (%) = 453 [M⁺+ 1] (40), 452 [M⁺] (100), 348 (30), 347 (70),

-18), 162.80 and 163.80 (s, carbonyl groups) ppm. IR (KBr): ν =

˜

Eur. J. Org. Chem. 2006, 335–350

www.eurjoc.org

347

A. A. Aly, S. Ehrhardt, H. Hopf, I. Dix, P. G. Jones

2930 cm^–1(m), 2860 (m), 1900 (s), 1840 (s), 1770 (s), 1500 (m), 1440 155 °C. ¹H NMR: δ = 2.56 (s, 3 H, CH₃), 2.74–3.77 (m, 8 H, ethano

FULL PAPER

(m), 1350 (m), 1290 (s), 1180 (m), 1150 (m), 930 (s), 890 (m). UV

(acetonitrile): λ_max(lg ε) = 213 nm (4.44), 236 (4.19), 304 (4.08),

380 (3.51), 401 (3.40). MS (70 eV): m/z (%) = 342 (83) [M⁺], 238

(46), 210 (14), 165 (22), 105 (46), 104 (100), 78 (29), 57 (18).

C₂₃H₁₈O₃(342.39): calcd. C 80.68, H 5.30; found C 80.70, H 5.30.

bridges), 3.93 (s, 3 H, OCH₃), 3.96 (s, 3 H, OCH₃), 5.69 (br. s, 2

H, 16-,17-H), 6.44–6.51 (m, 2 H, 19-,20-H), 6.75 and 6.77 (AB-q,

J = 7.3 Hz, 2 H, 11-,12-H), 7.59 (s, 1 H, 5-H) ppm. ¹³C NMR: δ

= 20.32 (q, CH₃), 32.87, 34.31, 34.79, 35.84 (t, C-1,-2,-13,-14),

52.38 (q, OCH₃), 52.67 (q, OCH₃), 128.19, 128.35, 129.38, 131.67,

131.81, 132.79, 133.90 (d, C-5,-11,-12,-16,-17,-19,-20), 129.63,

130.47, 130.67, 130.85, 136.03, 136.37, 136.84, 137.78, 138.12 (s, C-

3,-4,-6,-7,-8,-9,-10,-15,-18), 169.12 and 170.23 (s, carbonyl groups)

b) of Diesters 26a–c: A mixture of DDQ (3.15 g, 14.0 mmol) and

the diester 26a (5.2 g, 14.0 mol) in 400 mL of chlorobenzene was

refluxed for 2 h. After cooling to room temp. the produced hydro-

quinone was removed by filtration and thoroughly washed with

dichloromethane: 3.74 g (71%) of 55a, colorless plates (ethanol/

ppm. IR (KBr): ν = 2920 cm^–1(w), 2860 (w), 1725 (s), 1430 (m),

˜

1285 (s), 1230 (s), 1200 (s), 1170 (m), 1100 (m), 880 (m), 800 (m).

UV (methanol): λ_max(lg ε) = 213 nm (4.12), 230 (4.36), 274 (4.31),

311 (3.54). MS (70 eV): m/z (%) = 388 (92) [M⁺], 374 (21), 357 (15),

284 (100), 269 (52), 240 (43), 225 (24), 221 (39), 105 (41), 78 (37).

C₂₅H₂₄O₄(388.46): calcd. C 77.30, H 6.23; found C 77.64, H 6.33.

1

ether), m.p. 130–131 °C. H NMR: δ = 2.86–3.83 (m, 8 H, ethano

bridges), 3.96 (s, 3 H, COOCH₃), 4.06 (s, 3 H, COOCH₃), 5.71 (br.

s, 2 H, 16-, 17-H), 6.45–6.54 (m, 2 H, 19-,20-H), 6.81 and 6.83

(AB-q, J = 7.4 Hz, 2 H, 2 H, 11-,12-H), 7.82 and 7.92 (AB, J =

8.7 Hz, 2 H, 5-,6-H) ppm. ¹³C NMR: δ = 32.88, 34.31, 34.79, 36.03

(t, C-1,-2,-13,-14), 52.40 (q, –OCH₃), 52.57 (q, –OCH₃), 124.13,

129.18, 129.66, 131.22, 131.62, 131.97, 133.05, 134.80 (d, C-5,-6,

-11,-12,-16,-17,-19,-20), 126.00 (2×), 136.89, 136.97, 137.95 (2×),

138.16, 138.58 (s, C-3,-4,-7,-8,-9,-10,-15,-18), 166.96 and 170.53 (s,

By the same procedure from diester 26c (4 g, 10.0 mmol) DDQ

(2.27 g, 10.0 mmol) in 20 mL of chlorobenzene was prepared 55c

(2.11, 54%) as colorless needles (ethanol), m.p. 136–137 °C. ¹H

NMR: δ = 2.79 (s, 3 H, CH₃), 2.67–3.99 (m, 8 H, ethano bridges),

3.94 (s, 3 H, OCH₃), 4.04 (s, 3 H, OCH₃), 5.64–5.87 (m, 2 H, 16-,

17-H), 6.50–6.56 (m, 2 H, 19-,20-H), 6.76 and 6.81 (AB-q, 2 H, J

= 7.4 Hz, 11-,12-H), 7.68 (s, 1 H, 6-H) ppm. ¹³C NMR: δ = 24.20

(q, CH₃), 34.73, 35.40, 36.61, 38.73 (t, C-1,-2,-13,-14), 52.44 (q,

OCH₃), 52.56 (q, OCH₃), 129.80, 130.79, 131.02, 131.37, 135.62,

136.28, 136.72 (d, C-6,-11,-12, 16,-17,-19,-20), 125.14, 127.96,

129.51, 132.92, 134.59, 137.71, 137.96, 138.41, 138.71 (s, C-3,-4,

-5,-7,-8,-9,-10,-15,-18), 167.18 and 170.97 (s, carbonyl groups) ppm.

carbonyl groups) ppm. IR (KBr): ν = 2940 cm^–1(m), 2900 (m),

˜

2840 (m), 1740 (s), 1725 (s), 1590 (m), 1580 (m), 1450 (s), 1400 (m),

1270 (s), 1230 (s), 1190 (s), 1155 (s), 1140 (m), 1080 (s), 980 (m),

950 (m). UV (methanol): λ_max(lg ε) = 213 nm (4.36), 231 (4.35),

276 (4.24), 312 (3.56), 350 (3.22). MS (70 eV): m/z (%) = 374 (72)

[M⁺], 270 (100), 239 (48), 226 (17), 152 (32), 140 (18), 105 (22), 104

(31), 103 (32), 78 (32). C₂₄H₂₂O₄(374.44): calcd. C 76.99, H 5.92;

found C 77.18, H 5.89.

IR (KBr): ν = 2990 cm^–1(m), 2950 (m), 1735 (s), 1725 (s), 1580

˜

By the same procedure from 26b (2.34 g, 6.0 mmol) and DDQ

(1.36 g, 6.0 mmol) in 160 mL of chlorobenzene was obtained 55b

(1.56 g, 67%) within 28 h as colorless needles (ethanol), m.p. 154–

(m), 1435 (s), 1370 (m), 1290 (m), 1260 (s), 1225 (s), 1190 (m), 880

(m), 800 (m), 785 (m). UV (methanol): λ_max(lg ε) = 213 nm (4.36),

227 (4.33), 275 (4.31), 344 (3.38). MS (70 eV): m/z (%) = 388 (49)

Table 1. Crystal data collection and refinement parameters for compounds 47, 48, and 50.

Compound

47

48

50·½C₆H₁₄

Formula

M_r

C₁₆H₁₂Cl₄O₂

378.06

colorless prism

0.58×0.26×0.24

monoclinic

C2/c

C₁₇H₁₄Cl₄O₂

392.08

colorless prism

0.55×0.42×0.24

monoclinic

P2₁/c

C₂₈H₂₆Cl₄O₂

536.29

colorless prism

0.44×0.42×0.38

Monoclinic

P2₁/n

Crystal habitus

Crystal size [mm]

Crystal system

Space group

Cell constants

a [Å]

b [Å]

c [Å]

α [°]

16.210(2)

8.7869(8)

23.255(3)

90

8.892(3)

23.990(6)

7.902(2)

90

8.5964(8)

10.9965(14)

26.667(3)

90

β [°]

109.162(8)

90

3128.7

8

1.605

0.759

97.34(3)

90

1671.9

4

1.558

0.713

0.80–0.96

800

98.498(8)

90

2493.2

4

1.429

0.500

γ [°]

V [Å³]

Z

D_x[Mg·m^–3]

µ [mm^–1]

Transmissions

F(000)

0.89–0.98

1536

0.85–0.91

1112

T [°C]

2θ_max

–100

50

–130

50

–100

50

No. of reflections

measured

unique

2854

2745

0.018

201

0.084

0.033

0.92

3321

2952

0.017

211

0.083

0.033

1.09

4939

4381

0.016

308

0.075

0.032

0.92

R_int

Parameters

wR(F², all reflections)

R[F, Ͼ4σ(F)]

S

max. ∆ρ (e/Å³)

0.31

0.26

0.23

348

www.eurjoc.org

Eur. J. Org. Chem. 2006, 335–350

Cycloadditions to Alkenyl[2.2]paracyclophanes

FULL PAPER

[M⁺], 284 (100), 269 (32), 240 (21), 213 (14), 195 (14), 165 (40), 152

(32), 131 (21), 104 (64), 91 (14), 78 (32). C₂₅H₂₄O₄(388.46): calcd.

C 77.30, H 6.23; found C 77.32, H 6.29.

[8]

[9]

H. Hopf, Naturwissenschaften 1983, 70, 349–358.

H. Hopf, F.-W. Raulfs, D. Schomburg, Tetrahedron 1986, 42,

1655–1663.

[10]

V. Rozenberg, E. Sergeeva, H. Hopf, in: Modern Cyclophane

Chemistry (Eds.: R. Gleiter, H. Hopf), Wiley-VCH, Weinheim,

2004, chapter 17, pp. 435–462.

H. Hopf, F.-W. Raulfs, Isr. J. Chem. 1985, 25, 210–216.

For the preparation of the phenanthrenophane 9 by a stilbene

photocyclization/oxidation see H. Hopf, C. Mlynek, S. El-Tam-

any, L. Ernst, J. Am. Chem. Soc. 1985, 107, 6620–6627.

E. H. Eltamany, Ph. D. Dissertation, Braunschweig, 1983; cf.

A. Burger, D. J. Abraham, J. P. Buckley, W. J. Kinnard, Mon-

atsh. Chem. 1964, 95, 1721–1728.

c) of Furan 52: A solution of 52 (0.45 g, 1 mmol) and DDQ (0.23 g,

1 mmol) in chlorobenzene (120 mL) was refluxed for 1 d. The mix-

ture was cooled to room temp. and dichloromethane (200 mL) was

added, causing the precipitation of DDQ-H₂. The precipitate was

filtered off and washed several times with dichloromethane until

the filtrate became colorless. The filtrates were combined and con-

centrated below 50 °C in vacuo. The product was collected, recrys-

tallized from trichloromethane/cyclohexane (1:3, v/v) and stored in

the dark under dry conditions until the spectral measurements

could be taken: 0.42 g (93%) of furanophane 56, yellow needles,

m.p. 220–222 °C. ¹H NMR: δ = 2.55–2.65 (m, 2 H, ethano bridges),

2.72–2.80 (m, 1 H, ethano bridge), 2.87–3.00 (m, 2 H, ethano brid-

ges), 3.08–3.22 (m, 2 H, ethano bridges), 3.65–3.70 (m, 1 H, ethano

bridge), 5.78 (dd, J = 7.8 and 1.7 Hz, 1 H, 13-H), 6.22 (dd, J = 7.8

and 1.8 Hz, 1 H, 12-H), 6.55 (dd, J = 8.0 and 1.8 Hz, 1 H, 15-H),

6.60–6.72 (m, 3 H, 7-,8-,16-H), 7.22 (d, J = 9.3 Hz, 1 H, 18-H),

7.33–7.38 (m, 2 H, Ph-para-H), 7.40–7.45 (m, 2 H, Ph-meta-H),

7.47–7.54 (m, 2 H, Ph-meta-H), 7.72 (d, J = 9.3 Hz, 1 H, 17-H),

7.79–7.84 (m, 2 H, Ph-ortho-H), 7.98–8.03 (m, 2 H, Ph-ortho-H)

ppm. ¹³C NMR: δ = 34.17, 34.63, 35.19, 36.11 (t, C-1,-2,-9,-10),

117.44, 118.64, 120.56, 120.97, 125.29, 126.85 (d each, Ph-H-ortho),

127.69, 127.93 (d each, Ph-H-para), 128.40 (d, C-18), 128.50,

128.90 (d each, Ph-H-meta), 129.03 (Ar-C), 131.23, 131.52, 133.25,

133.30 (PC-CH), 133.41, 133.39, 133.98 (Ar-C), 134.28, 136.62

(PC-CH), 136.98 (d, C-17), 138.31 (s, C-19), 139.50 (s, C-21),

[11]

[12]

[13]

[14]

E. A. Truesdale, D. J. Cram, J. Org. Chem. 1980, 45, 3974–

3981; cf. S. Ehrhardt, Ph. D. Dissertation, Braunschweig,

1987.

[15]

[16]

[17]

H. Hopf, in: Modern Cyclophane Chemistry (Eds.: R. Gleiter,

H. Hopf), Wiley-VCH, Weinheim, 2004, chap. 7, pp. 189–210.

H. Hopf, J.-H. Shin, H. Volz, Angew. Chem. 1987, 99, 594–595;

Angew. Chem. Int. Ed. Engl. 1987, 26, 564–565.

P. G. Jones, P. Bubenitschek, H. Hopf, Z. Pechlivanidis, Z. Kri-

stallogr. 1993, 208, 136–138; P. G. Jones, P. Bubenitschek, H.

Hopf, B. Kaiser, Z. Kristallogr. 1995, 210, 548–549; cf. L.

Ernst, K. Ibrom, in: Modern Cyclophane Chemistry (Eds.: R.

Gleiter, H. Hopf), Wiley-VCH, Weinheim, 2004, chapter 15,

pp. 381–414.

A mixture of 16 and 17 was used in this cycloaddition experi-

ment, but after work-up the Z-isomer 17 was recovered un-

changed.

J. Hukki, Acta Chem. Scand. 1951, 5, 31–53.

Th. Wagner-Jauregg, Justus Liebigs Ann. Chem. 1931, 491, 1–

13.

[18]

[19]

[20]

147.80 (s, C-20), 148.90 (s, C-22) ppm. IR (KBr): ν = 3058–

˜

3006 cm^–1(m), 2988–2851 (m), 1580 (s), 1480 (s), 1460 (s), 1290

(m), 1070 (m). MS (70 eV): m/z (%) = 451 [M⁺+ 1] (50), 450 [M⁺]

(76), 346 (76), 345 (100), 241 (14), 228 (32), 202 (14), 105 (24), 77

(30). C₃₄H₂₆O (450.58): calcd. C 90.63, H 5.82; found C 90.50, H

5.80.

[21]

[22]

K. Alder, H. Niklas, Justus Liebigs Ann. Chem. 1954, 585, 97–

114.

C. F. Huebner, E. M. Donoghue, C. J. Novak, L. Dorfman, E.

Wenkert, J. Org. Chem. 1970, 35, 1149–1154. O. Diels and K.

Alder who first carried out this experiment postulated the for-

mation of a diazetidine as the reaction product (O. Diels, K.

Alder, Justus Liebigs Ann. Chem. 1926, 450, 237–254).

E. Koerner von Gustorf, D. V. White, B. Kim, D. Hess, J. Leit-

ich, J. Org. Chem. 1970, 35, 1155–1165.

B. T. Gillis, P. E. Beck, J. Org. Chem. 1962, 27, 1947–1951; cf.

B. Franzus, J. H. Surridge, J. Org. Chem. 1962, 27, 1951–1957.

A. van der Gen, J. Lakeman, U. K. Pandit, H. O. Huisman,

Tetrahedron 1965, 21, 3641–3649.

H. Hopf, C. Marquard, in: Strain and its Implications in Or-

ganic Chemistry (Eds.: A. de Meijere, S. Blechert), Kluwer Aca-

demic Publishers, Dordrecht, 1989, 297–332.

R. Cookson, S. S. H. Gilani, I. D. R. Stevens, J. Chem. Soc., C

1967, 1905–1909.

Y. C. Lai, S. E. Mallakpour, G. B. Butler, G. J. Palenik, J. Org.

Chem. 1985, 50, 4378–4381. cf. K. B. Wagener, S. R. Turner,

G. B. Butler, J. Polym. Sci., Part B 1972, 805.

The reaction of 7 and 10e under harsher conditions (toluene,

reflux, 3 d) has been reported to yield 4-(2Ј,2Ј-dicyanoe-

thenyl[2.2]paracyclophane): A. A. Aly, A. A. Mourad, Tetrahe-

dron 1993, 49, 7325–7336.

X-ray Crystallography: A summary of the crystal data, data collec-

tion and refinement parameters for the three crystal structures re-

ported in this paper is given in Table 1. Structure Determination of

47 and 50: Intensities were registered with Mo-K_αradiation (λ =

0.71073 Å) with a Siemens P4 diffractometer fitted with an LT-2

low-temperature attachment. Absorption corrections were based

on ψ scans. Structures were refined anisotropically by full-matrix

least-squares on F², using the program SHELXL-97.^[38]The hydro-

gen atoms were refined with rigid methyl groups or a riding model.

Structure determination of 48: Measurements were made with a

Stoe STADI-4 diffractometer. All other details as above.

[23]

[24]

[25]

[26]

[27]

[28]

CCDC-238102 (for 50), -238103 (for 47), -238104 (for 48) contain

the supplementary crystallographic data for this paper. These data

can be obtained free of charge from The Cambridge Crystallo-

graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

[29]

[1] H. Hopf, A. A. Aly, V. N. Swaminathan, L. Ernst, I. Dix, P. G.

Jones, Eur. J. Org. Chem. 2005, 68–71.

[2] H. Hopf, Angew. Chem. 1972, 84, 471; Angew. Chem. Int. Ed.

Engl. 1972, 11, 419.

[3] H. Hopf, J. Kleinschroth, I. Böhm, Org. Synth. 1981, 60, 41–

48.

[30]

[31]

A. T. Blomquist, Y. C. Meinwald, J. Am. Chem. Soc. 1957, 79,

5316–5317.

C. F. Huebner, P. L. Strachan, E. M. Donoghue, N. Cahoon,

L. Dorfman, R. Margerison, E. Wenkert, J. Org. Chem. 1967,

32, 1126–1130.

We thank Dr. Jörg Grunenberg (Technical University

Braunschweig) for these calculations.

This interpretation assumes again that in the actual attack of

10e on 20 one reaction path is favored strongly over all other

conceivable alternatives.

J. K. Williams, D. W. Wiley, B. C. McKusick, J. Am. Chem.

Soc. 1962, 84, 2210–2215.

[4] I. Böhm, H. Herrmann, K. Menke, H. Hopf, Chem. Ber. 1978,

[32]

[33]

111, 523–537.

[5] J. Kleinschroth, H. Hopf, Tetrahedron Lett. 1979, 20, 969–972.

[6] A. A. Aly, H. Hopf, L. Ernst, Eur. J. Org. Chem. 2000, 3021–

3029.

[7] H. Hopf, B. Witulski, Pure Appl. Chem. 1993, 65, 47–56; and

references cited therein; cf. H. Hopf, B. Witulski, P. G. Jones,

D. Schomburg, Liebigs Ann. 1995, 609–612.

[34]

Eur. J. Org. Chem. 2006, 335–350

www.eurjoc.org

349

A. A. Aly, S. Ehrhardt, H. Hopf, I. Dix, P. G. Jones

FULL PAPER

[35] L. Horner, H. Merz, Justus Liebigs Ann. Chem. 1950, 570, 89–

120; cf. K. Th. Finley, in The Chemistry of Quinoid Compounds

(Eds.: S. Patai, Z. Rappoport), John Wiley & Sons, New York,

1988, vol. II, pp. 538–717.

[36] A. Marrocchi, L. Minuti, A. Taticchi, I. Dix, H. Hopf, E.

Gacs-Baitz, P. G. Jones, Eur. J. Org. Chem. 2001, 4259–4268;

cf. L. Minuti, A. Taticchi, A. Marrocchi, E. Gacs-Baitz, R.

Galezzi, Eur. J. Org. Chem. 1999, 3155–3163.

[37] W. Su, S. Urgaonkar, J. Verkade, Org. Lett. 2004, 6, 1421–1424;

cf. F. Kunckell, W. Dettmar, Ber. Dtsch. Chem. Ges. 1903, 36,

771–773.

[38] G. M. Sheldrick, SHELXL-97, University of Göttingen, Ger-

many, 1997.

Received: June 3, 2005

Published Online: November 10, 2005

350

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Cycloadditions to alkenyl[2.2]paracyclophanes

DOI: 10.1002/ejoc.200500396

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