Acidified Alcohols as Agents to Introduce and Exchange Alkoxyls on the Periphery of Helicenes

Article abstract of DOI:10.1021/jo9914972

Alcohols containing HCl transform the hydroquinone reduction-products of helicenebisquinones into p-alkoxyphenols that have the alkoxyls specifically on the peripheries of the helices. The reactions are quick, and the yields are high. Alkoxyls at the 6-position are replaced also, but only after 2 h at 60°C, not after the 5 min at 25°C sufficient to replace the peripheral hydroxyls of the hydroquinones. After the remaining inside hydroxyls of a dihydroxytetramethoxy[6]helicene prepared by this procedure have been converted into camphanates, one diastereomer crystallizes from solution, allowing an enantiomer resolution to be carried out on a large scale. By then simply reapplying the procedure with alcoholic acid, a variety of resolved dihydroxytetraalkoxy[6]helicenes can be prepared in excellent yields without resolution procedures having to be developed for each. Similar procedures are effective when applied to a [7]carbohelicene.

Full text of DOI:10.1021/jo9914972

806
J . Org. Chem. 2000, 65, 806-814
Acid ified Alcoh ols a s Agen ts to In tr od u ce a n d Exch a n ge Alk oxyls
on th e P er ip h er y of Helicen es
Spencer D. Dreher,† Kamil Paruch,† and Thomas J . Katz*
The Department of Chemistry, Columbia University, New York, New York 10027
Received September 22, 1999
Alcohols containing HCl transform the hydroquinone reduction-products of helicenebisquinones
into p-alkoxyphenols that have the alkoxyls specifically on the peripheries of the helices. The
reactions are quick, and the yields are high. Alkoxyls at the 6-position are replaced also, but only
after 2 h at 60 °C, not after the 5 min at 25 °C sufficient to replace the peripheral hydroxyls of the
hydroquinones. After the remaining inside hydroxyls of a dihydroxytetramethoxy[6]helicene
prepared by this procedure have been converted into camphanates, one diastereomer crystallizes
from solution, allowing an enantiomer resolution to be carried out on a large scale. By then simply
reapplying the procedure with alcoholic acid, a variety of resolved dihydroxytetraalkoxy[6]helicenes
can be prepared in excellent yields without resolution procedures having to be developed for each.
Similar procedures are effective when applied to a [7]carbohelicene.
Sch em e 1
In tr od u ction
Helicenes with multiple alkoxy substituents on their
periphery are the precursors of a number of new materi-
als, including helical discotic liquid crystals,1 self-as-
sembling corkscrew structures with significant optical
properties,2 helical fully conjugated polymers,3 and a
helical ligand for asymmetric catalysis.4 However, the
introduction of the correct alkoxy groups at the right
positions can sometimes be difficult. For example, to
convert the [6]helicenebromoquinone 1 (X ) Br) into
methoxysalicylaldehyde 3 (X ) CHO),3 the steps used to
place the methoxyls on the outside of the helix and the
hydroxyls on the inside (Scheme 1) included selectively
cleaving the less hindered esters of 2 (X ) Br), converting
the resulting phenols into methyl ethers, and then
cleaving the remaining esters.
Sch em e 2
In this paper, we describe a much simpler procedure
for effecting transformations such as these in a variety
of helicenes. The procedure is an application of a reaction
discovered by Russig5 in 1900 (Scheme 2) that converts
naphthalene-1,4-diols selectively into monoalkyl ethers
and unsymmetrical naphthalene-1,4-diols specifically
into one of the two possible monoethers (in Russig’s case,
4 to 5, R ) CO2H).6,7 Russig’s reaction is related to one
discovered by Liebermann in 1882,8 in which an alcohol
and HCl transform R- and â-naphthols into naphthyl
alkyl ethers.9 It was not until 1980 that Laatsch7b applied
this transformation to a number of naphthalene-1,4-diols
and proposed a plausible mechanism, proceeding by way
of 6.10 This transformation, which we call the Russig-
Laatsch reaction, puts the alkoxyl on the less hindered
of the 1,4-oxygens and in the case of helicenes, as
described below, does so with high specificity and yield.
(6) Subsequently 4, with R ) CH3, was transformed into the ethyl
ether analogous to 5 by: (a) Tishler, M.; Fieser, L. F.; Wendler, N. L.
J . Am. Chem. Soc. 1940, 62, 1982. It was transformed into the methyl
ether 5 by: (b) Bondinell, W. E.; DiMari, S. J .; Frydman, B.; Matsu-
moto, K.; Rapoport, H. J . Org. Chem. 1968, 33, 4351, and by Laatsch.7b
Related examples, with R ) OCH3, were found by: (c) Baldwin, J . E.;
Basson, H. H. J . Org. Chem. 1969, 34, 2788, and by Laatsch.7b Further
examples with R ) Br and Cl were found by Laatsch.7b
(7) (a) Laatsch, H. Tetrahedron Lett. 1976, 3287. (b) Laatsch, H.
Liebigs Ann. Chem. 1980, 140. (c) Laatsch, H. Liebigs Ann. Chem. 1980,
1321. (d) Laatsch, H. Liebigs Ann. Chem. 1985, 251. (e) Laatsch, H. Z.
Naturforsch., B: Anorg. Chem., Org. Chem. 1986, 41B, 377. (f) Laatsch,
H. Liebigs Ann. Chem. 1991, 385. (g) Laatsch, H. Z. Naturforsch., B:
Chem. Sci. 1993, 48, 1291. (h) Kuroki, N.; Kitao, T.; Konishi, K. Koˆgyoˆ
Kagaku Zasshi 1956, 59, 1056.
(8) (a) Liebermann, C.; Hagen, A. Chem. Ber. 1882, 15, 1427. (b)
Gattermann, L. Liebigs Ann. Chem. 1888, 72, 244. (c) Bell, K. H.;
McCaffery, L. F. Aust. J . Chem. 1993, 46, 731. The discovery has often
been attributed to Gattermann, but Gattermann acknowledged learn-
ing the procedure from “Dr. Henriques of Berlin”, presumably Robert
Henriques, who at the time worked in the same laboratory as
Liebermann. Henriques is said to have recommended the use of sulfuric
acid for the conversion of R-naphthol into its ethyl ether, and
Gattermann used this acid to prepare R-naphthyl methyl ether.
†These authors contributed equally to the research.
(1) Nuckolls, C.; Katz, T. J . J . Am. Chem. Soc. 1998, 120, 9541.
(2) (a) Nuckolls, C.; Katz, T. J .; Castellanos, L. J . Am. Chem. Soc.
1996, 118, 3767. (b) Nuckolls, C.; Katz, T. J .; Katz, G.; Collings, P. J .;
Castellanos, L. J . Am. Chem. Soc. 1999, 121, 79. (c) Verbiest, T.; Van
Elshocht, S.; Kauranen, M.; Hellemans, L.; Snauwaert, J .; Nuckolls,
C.; Katz, T. J .; Persoons, A. Science (Washington, D.C.) 1998, 282, 913.
(d) Busson, B.; Kauranen, M.; Nuckolls, C.; Katz, T. J . Persoons, A.
Phys. Rev. Lett. 2000, 84, 79. (e) Fox, J . M.; Katz, T. J .; Van Elshocht,
S.; Verbiest, T.; Kauranen, M.; Persoons, A.; Thongpanchang, T.;
Krauss, T.; Brus, L. J . Am. Chem. Soc. 1999, 121, 3453.
(3) Dai, Y.; Katz, T. J . J . Org. Chem. 1997, 62, 1274.
(4) Dreher, S. D.; Katz, T. J .; Lam, K.-C.; Rheingold, A. L. J . Org.
Chem. 2000, 65, 815.
(5) Russig, F. J . Prakt. Chem. 1900, 62(2), 30.
10.1021/jo9914972 CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/16/2000

Alkoxyls on the Periphery of Helicenes
J . Org. Chem., Vol. 65, No. 3, 2000 807
(R1 ) R2 ) Me, Et, and n-Bu) in 93%, 95%, and 90%
yields, respectively. Helicene 7 with R1 ) TIPS was
synthesized as described in the Experimental Section,
from the TIPS-enol ether of 2,7-diacetylnaphthalene and
p-benzoquinone. This helicene is similar to one prepared
previously, 7 with R1 ) t-BuMe2Si,12 but the procedure
used here, similar to one used previously to prepare other
helicenebisquinones,12,14 is simpler. Aryl silyl enol ethers
are easy to synthesize and, when compared to their alkyl
analogues, give better yields of helicenebisquinones upon
reaction with p-benzoquinone,12,14 Accordingly, the use
described here of alcoholic acid to replace siloxyls by
alkoxyls could be generally advantageous. It surmounts
the need for desilylation reagents, such as CsF, and for
expensive and toxic alkylating agents.15
Sch em e 3a
a
Reaction conditions: (a) aqueous Na2S2O4; (b) EtOH, HCl,
(ClCH2)2.
The Russig-Laatsch reactions can also be carried out
with long-chain alcohols, which previously had not been
reported. Presumably because in previous procedures the
alcohols were used in large excess, as the solvents, those
that boil at high temperatures were difficult to separate
from the product. However, after 8 (R1 ) TIPS) has been
warmed for 2 h at 60 °C with a mixture of 10 times as
many moles of dodecanol saturated with HCl and an
equal volume of (ClCH2)2, the excess dodecanol can be
removed by trituration with methanol, which selectively
dissolves it. The yield of 9 (R1 ) R2 ) n-C12H25) was 80%.
It probably would have been higher had not some of the
helicene dissolved in the methanol.
This procedure is easy to carry out, and it can be used
to introduce a variety of alkoxy groups in positions such
as that occupied in 3 by the methoxyl, para to the
hydroxyl. Remarkably, if desired, it also can be used to
exchange alkoxyls at positions such as those occupied in
3 by the OR groups. In addition, because the bis-
alkoxyphenols from these reactions are easier to resolve
into enantiomers than the corresponding bis-1,4-diols, the
alkoxyphenols can be used to prepare nonracemic bis-
quinones such as 1 (X ) H) more easily than was
heretofore possible.
Evidence that the alkyl groups are on the periphery
and not in the positions that in 9 are occupied by the
hydroxyls was shown unambiguously by the crystal
structure16 of 10, the dextrorotatory diester of 9 (R1 )
R2 ) Me) with (S)-(-)-camphanic acid (see below). In
none of these reactions was evidence found of the
products in which the phenols on the inside of the helices,
those labeled explicitly as OHs in structure 9, had been
alkylated. Thus, even after 7 h at 60 °C, none of the
product like 9 (R1 ) R2 ) Me), but with OH replaced by
OMe, was found when 8 (R1 ) TIPS) was combined with
methanolic HCl in 1,2-dichloroethane.
Resu lts
The procedure described here for the Russig-Laatsch
reactions was developed in preliminary experiments. HCl
gas saturated the alcohols before they were used and,
unlike in Laatsch’s procedure,7a-g was not subsequently
bubbled into the reaction mixtures. Because the helicenes
were often insoluble in the alcohols, 1,2-dichloroethane
(bp 83 °C) was usually added as a cosolvent.
Th e Ru ssig-La a tsch Rea ction s of [6]Helicen e-
tetr a ols 8. By means of aqueous sodium dithionite
(Na2S2O4),11 7 (R1 ) Me)12 was reduced to 8 (R1 ) Me,
Scheme 3), and this hydroquinone was combined with
ethanolic HCl plus (ClCH2)2 for 5 min at room temper-
ature, giving 9 (R1 ) Me, R2 ) Et) in 89% yield. If instead
the reaction was carried out at 60 °C for 2 h, the
methoxyls as well were completely replaced by ethoxyls.
Under these conditions, 9 (R1 ) R2 ) Et) was obtained,
and the yield was 95%.13
Similarly, 7 (R1 ) TIPS) was reduced to 8 (R1 ) TIPS),
which with MeOH, EtOH, or BuOH, each saturated with
HCl and mixed with (ClCH2)2, gave, after 2 h at 60 °C, 9
The Russig-Laatsch reaction also can be used to
exchange one set of alkoxyls for another. Thus, when 9
(R1 ) R2 ) Me) was combined for 2 h with HCl in EtOH
at 75 °C or in BuOH or dodecanol at 90 °C, helicenes were
obtained in which the methoxyls were replaced by
ethoxyls, butoxyls, or dodecyloxyls. The yields were 93,
91, and 75%, respectively. These transformations pro-
ceeded more efficiently when methanol was removed as
it formed, to prevent it from competing with the other
alcohols for attachment to the aromatic nucleus. This was
accomplished by carrying out the reactions above the
boiling point of MeOH and capturing the distilled metha-
nol in a cold bulb.
(9) The reaction was extended to the conversion of resorcinol to its
monomethyl ether by: (a) Wallach, O.; Wu¨sten, M. Chem. Ber. 1883,
16, 149. It was extended to the conversion of phloroglucinol to its
diethyl and dimethyl ethers by: (b) Will, W.; Albrecht, K. Chem. Ber.
1884, 17, 2098. (c) Will, W. Chem. Ber. 1888, 21, 602. The former
extension was developed further by: (d) Merz, V.; Strasser, H. J . Prakt.
Chem. 1900, 61, 103. The latter extension was developed further by:
(e) Weidel, H.; Pollak, J . Monatsh. Chem. 1900, 21, 15, and references
therein.
(10) For the tautomerism of phenols, see: (a) Forse´n, S.; Nilsson,
M. In The Chemistry of the Carbonyl Group, Vol. 2; Zabicky, J ., Ed.;
Interscience: New York, 1970; pp 168-183. (b) Thomson, R. H. Quart.
Rev. Chem. Soc. 1956, 10, 27. (c) Pearson, M. S.; J ensky, B. J .; Greer,
F. X.; Hagstrom, J . P.; Wells, N. M. J . Org. Chem. 1978, 43, 4617.
(11) Reference 2b and references in footnote 29 therein.
(12) Katz, T. J .; Liu, L.; Willmore, N. D.; Fox, J . M.; Rheingold, A.
L.; Shi, S.; Nuckolls, C.; Rickman, B. H. J . Am. Chem. Soc. 1997, 119,
10054.
(14) (a) Fox, J . M.; Goldberg, N. R.; Katz, T. J . J . Org. Chem. 1998,
63, 7456. (b) Dreher, S. D.; Weix, D. J .; Katz, T. J . J . Org. Chem. 1999,
64, 3671.
(15) Oriyama, T.; Noda, K.; Yatabe, K. Synlett 1997, 701.
(16) Thongpanchang, T.; Paruch, K.; Katz, T. J .; Rheingold, A. L.;
Lam, K.-C..; Liable-Sands, L. J . Org. Chem., in press.
(13) This replacement took place even at ambient temperatures
when the reaction times were greater than 5 min.

808 J . Org. Chem., Vol. 65, No. 3, 2000
Dreher et al.
Resolvin g th e En a n tiom er s of 9. Helicenebisquino-
nes have previously been resolved into their enantiomers
by a procedure in which the quinones were reduced to
hydroquinones, the latter’s phenolic hydroxyls were
acylated with camphanoyl chloride, and the resulting
diastereomeric tetracamphanates were separated by
chromatography.2b,14 The camphanate esters, when com-
pared to a number of esters of nonracemic acids, have
proven to be particularly effective, for reasons that are
now understood,16 and the procedure using them has
been applied to a large number of resolutions.2b,14 Since
the experiments described in this manuscript produce
helicenediols, the possibility was tested that their dias-
tereoisomeric dicamphanates would also be easy to
prepare and separate even though they have only two
camphanate groups per molecule, not four as in the
helicenes previously resolved.
solutions of CAN in aqueous CH3CN. In this way (-)-9
(R1 ) R2 ) Me, Et, n-Bu, and n-C12H25) were transformed
into (-)-7 (R1 ) Me, Et, n-Bu, and n-C12H25) in yields of
71%, 75%, 73%, and 73%, respectively, and (+)-9 (R1 )
R2 ) Me) into (+)-7 (R1 ) Me) in a yield of 74%.
If in place of CAN, the agent used for the oxidation of
(-)-9 (R1 ) R2 ) n-C12H25) was benzeneseleninic anhy-
dride in THF,19 the product was a mixture of bis-o-, ortho-
p-, and bis-p-quinones, unless 4 Å molecular sieves were
added to the reaction mixture. Then the pure o,o-quinone
(-)-11 (R ) n-C12H25) could be obtained in a yield of 68%,
uncontaminated by the bis-p-quinone 7 (R1 ) n-C12H25).
The tests were carried out with 9 (R1 ) R2 ) Me). This
diol was chosen because in the course of related work
with a [5]helicenol (structure 16 below), the discovery was
made that when the side chains are methoxyls, chroma-
tography is not required to separated the diastereomeric
camphanates as it is when the side chains are large
alkoxy groups.4 One diastereomer crystallizes.
An experimental procedure was developed that trans-
forms diol 9 (R1 ) R2 ) Me) into its dicamphanate, and
because it uses only 3 mol of camphanoyl chloride per
mole of the helicenediol, it is far superior to the one
previously used to convert related tetraols into their
tetracamphanates.2b,14 That procedure used 12-15 mol
of camphanoyl chloride per mole of helicenetetraol. In the
new procedure the diol and the acid chloride are refluxed
with triethylamine and 4-(dimethylamino)pyridine
(DMAP) in 1,2-dichloroethane for 2 h. In the older
procedure DMAP was not used.
Sim ila r Tr a n sfor m a tion s of a [7]Ca r boh elicen e.
The results of experiments carried out with a [7]heli-
cenebisquinone, 12,14a were similar. Reducing 12 with
zinc and AcOH,20 and combining the resulting bis-
hydroquinones with dodecanol, HCl, and 1,2-dichloroet-
hane converted it cleanly into 13. The diastereomeric
dicamphanates separated easily upon chromatography,
and when the camphanate esters were removed, the
enantiomers of 13 were both obtained in good yields.
These phenol ethers could be oxidized selectively to either
bis-p- or bis-o-quinones. CAN cleanly oxidized (+)-13 to
(+)-12 in 75% yield. Benzeneseleninic anhydride in THF
containing 4 Å molecular sieves oxidized (+)-13 to the
bis-o-quinone, (+)-14, in 64% yield.
Moreover, the dextrorotatory dicamphanate of 9 (R1 )
R2 ) Me, structure 10) crystallizes from a mixture of
ethyl acetate and cyclohexane, and 5.7 g was isolated, a
66% yield. To obtain the levorotatory dicamphanate,
small amounts of the (+)-isomer were removed from the
remaining material by passing it in a mixture of hexane
and ethyl acetate through a small plug of silica gel. A
62% yield of the (-)-isomer (5.2 g) was obtained. An
additional 8-9% of each diastereomer could be isolated
from residual material by means of chromatography. The
camphanate groups could then be removed by combining
the esters with potassium hydroxide in EtOH, and after
workup, the nonracemic phenols 9 (R1 ) R2 ) Me) were
isolated, the (+)-enantiomer in 93% yield, and the (-)-
enantiomer in 99% yield. Noteworthy is the power of the
Russig-Laatsch reaction to transform these substances
Discu ssion
We suppose, as Laatsch proposed,7b that the reactions
of naphthalene-1,4-diols with alcohols and acid proceed
by the alcohols adding to the carbonyls of the dione
tautomers. The selectivity that leads to only one of the
two p-hydroxyls alkylating would then originate in the
inability of monoethers of such structures to tautomerize
into 9 (R1 ) R2 ) Et) in 93% yield, into 9 (R1 ) R2
)
n-Bu) in 91% yield, and into 9 (R1 ) R2 ) n-C12H25) in
75% yield, making it possible to obtain them in nonrace-
mic form without a separate resolution procedure having
to be developed for each.17 Accordingly, the preparations
of a variety of helicenes benefit from the simplicity with
which 9 (R1 ) R2 ) Me) can be resolved.
Oxid a tion of Ru ssig-La a tsch Rea ction P r od u cts
9. The phenol ethers 9, like other monoalkyl ethers of
hydroquinones, can be oxidized by means of ceric am-
monium nitrate (CAN)18 to p-quinones. Although the
yields were poor when CAN and the phenols 9 were
combined simultaneously in mixtures of aqueous CH3-
CN and CH2Cl2, the yields were good when the phenol
ethers in CH2Cl2 were added slowly to rapidly stirred
(17) The helicenes are unlikely to racemize significantly during these
transformations as 1,16-dimethyl[6]helicene, an analogue of 9 that has
methyls in place of hydroxyls, has to be heated to 270 °C before its
half-life for racemization decreases to 7.4 h, and [6]helicene itself has
to be heated to 188 °C before its half-life for racemization decreases to
3 h [(a) Borkent, J . H.; Laarhoven, W. H. Tetrahedron 1978, 34, 2565.
(b) Martin, R. H.; Marchant, M. J . Tetrahedron Lett. 1972, 3707].
Moreover, the near-identity of the CD spectra of 9 and 7 (see below,
R1 ) R2 ) Et, n-Bu, and n-C12H25), which had been heated at 60 °C
for 2 h, and 9 and 7 R1 ) R2 ) Me, which had not, imply that the
transformations did not significantly change the enantiomeric purities.
(18) J acob, P., III; Callery, P. S.; Shulgin, A. T.; Castagnoli, N., J r.
J . Org. Chem. 1976, 41, 3627.
(19) Barton, D. H. R.; Finet, J . P.; Thomas, M. Tetrahedron 1988,
44, 6397.
(20) Helicene bisquinones can usually be reduced with either
Na2S2O4 or Zn and AcOH. In the case of 12, the reduction with Na2S2O4
was sluggish and Zn and AcOH reacted faster.

Alkoxyls on the Periphery of Helicenes
J . Org. Chem., Vol. 65, No. 3, 2000 809
Sch em e 4
to diones. The selectivity that leads to the alkoxy groups
being introduced at the periphery of the helicenes, rather
than on the insides of the structures, can, however, be a
consequence of either of two effects. It could be the result
of the R1O groups in the diketo-tautomer of 8 conjugating
with the carbonyls. Since such conjugation would stabi-
lize only the internal carbonyls;21 the alcohols would add
preferentially to those that are external.22 The other
possibility is that the selectivity arises from the much
greater steric congestion on the inside of the helicene
favoring addition to the less congested external carbonyls.
Evidence that the steric effect probably dominates was
provided in an experiment reported by Laatsch.7d He
showed that 6-ethoxynaphthalene-1,4-diol with methanol
and HCl gives a 3:2 mixture of its two possible mono-
methyl ethers,23 suggesting that electronic effects in the
absence of steric effects do not exert much influence.
Definitive evidence that in the helicenes it is not the
alkoxyl at the 6-position that accounts for the selectivity
(see structure 8 for the numbering), and accordingly that
steric effects must account for it, was provided by an
experiment in which this alkoxyl was missing. Thus,
when structure 8, but with an H in place of R1O,24 was
combined with HCl in MeOH and 1,2-dichloroethane for
2 h at 60 °C, it gave 9 (R1O ) H, R2 ) Me) in 85% yield.
If as much as 2% had been present of the products that
intermediate, rather than a hemiacetal. The pathway
followed when a helicene exchanges one R1O group for
another probably is similar to that followed when metha-
nolic p-toluenesulfonic acid at 100 °C converts 2-naphthol
into its methyl ether27 or when a mixture of ethanol and
hydrochloric acid at 180 °C converts phenol into its ethyl
ether.28 Scheme 4 summarizes the steps.
However, the temperatures at which the replacements
take place in the helicene structuresssee Scheme 3 and
the reactions of 9 (R1 ) R2 ) Me) with ethanol, butanol,
and dodecanolsare considerably lower than those used
by Liebermann and Gattermann to replace the hydroxyls
of 1- and 2-naphthols by ethoxyls,8a,b and the reaction
times are much shorter than those used by Bell and
McCaffrey to replace the hydroxyls of dihydroxy-
naphthols.8c The difference seems to be that the proto-
nation in Scheme 4, like other reactions of phenanthrenes
and naphthalenes with electrophiles, is facilitated by 8
and 9 being derivatives of 9-phenanthrol rather than of
1- or 2-naphthols. This suggests that 9-phenanthrol itself
might easily be converted into its ethyl ether by a mild
treatment with ethanolic acid, and indeed it is, in 82%
yield. The reagents were ethanolic HCl plus 1,2-dichlo-
roethane at 60 °C, and the reaction time was 2 h.29
Similarly, under the same conditions, but with methanol
in place of ethanol, 9-ethoxyphenanthrene was trans-
formed into 9-methoxyphenanthrene in almost quantita-
tive yield. Naphthalene derivatives, however, should be,
and are, less reactive. Ethanolic HCl in 1,2-dichloro-
ethane at 60 °C for 2 h had no effect on either 1- or
2-naphthols or on 1- or 2-methoxynaphthalenes.
1
in 9 had methoxyls in place of hydroxyls, the H NMR
analysis would have detected them. But it did not.25 The
steric effect might arise from crowding in the center of
the molecule either favoring structures with fewer atoms
on the inside of the helicene or restricting additions to
and departures from the central carbonyls so they occur
from the same direction, presumably the outside of the
helicene structure.
The strength of this steric effect is indicated by the
absence of detectable quantities of 1,4-dialkoxyhelicenes
in any of the products of the reactions described above
(even after 7 h at 60 °C). In contrast, Laatsch found that,
unlike sterically hindered naphthalene-1,4-diols (in his
case those that were 2-substituted7b), simpler and there-
fore less sterically hindered examples, while they usually
are selectively monoalkylated after brief exposure to
alcoholic solutions of HCl, do in at least three cases give
appreciable amounts of dialkylated derivatives.26
Prior to the replacement of the R1O and R2O groups of
8 and 9 reported here, there seems to have been only one
example of a transformation in which alcoholic acid
exchanged one alkyl group for another in an alkyl aryl
ether.6c The pathway followed when one R2O group in 9
exchanges for another can be envisioned as the reverse
of that followed when 9 is formed from 8, but with alcohol
taking the place of water. An acetal is therefore an
Con clu sion s
Acidified alcohols are superb reagents for introducing
and replacing alkoxy groups on the periphery of heli-
cenes. They make it possible to transform 7 (R1 ) TIPS),
which is particularly easy to synthesize, into 9 (R1 ) R2
) Me), which is particularly easy to resolve. Acidified
alcohols then transform these enantiomers into nonra-
cemic helicenes with other side chains, and CAN and
benzeneselininic acids oxidize these to nonracemic p- and
o-quinones that bear these side chains too. The ability
to introduce and replace alkoxy groups specifically on the
periphery of helicenes has also made it possible to
prepare a helical ligand for asymmetric synthesis.4 In
that application (Scheme 5), the easily synthesized helical
quinone 15 was converted selectively to phenol 16, which
could be resolved on a large scale and oxidized to 17, a
helical analogue of BINOL. This structure was named
[5]HELOL. Simple procedures for resolving helicenes and
for introducing different peripheral alkoxyl groups onto
helicene skeletons also promise to make it possible to
(21) (a) Kelly, T. R.; Gillard, J . W.; Goerner, R. N., J r.; Lyding, J .
M. J . Am. Chem. Soc. 1977, 99, 5513. (b) Kelly, T. R.; Parekh, N. D.;
Trachtenberg, E. N. J . Org. Chem. 1982, 47, 5009. (c) Rozeboom, M.
D.; Tegmo-Larsson, I.-M.; Houk, K. N. J . Org. Chem. 1981, 46, 2338.
(22) See ref 12 and footnotes 22, 55, and 56 therein.
(23) Laatsch did not determine which regioisomer predominated.
(24) Yang, B.; Liu, L.; Katz, T. J .; Liberko, C. A.; Miller, L. L. J .
Am. Chem. Soc. 1991, 113, 8993.
(25) 1H NMR spectrum of the crude reaction mixture showed no
peaks of >2% intensity at approximately 2.6 ppm, where the resonance
of the inside OMe of permethoxylated 9 (R1O ) H, R2 ) Me, OH )
OMe) appears (Yang, B. V. Ph.D. Dissertation, Columbia University,
1987).
(27) Wiberg, K. B.; Saegebarth, K. A. J . Org. Chem. 1960, 25, 832.
(28) Oae, S.; Kiritani, R. Bull. Chem. Soc. J pn. 1966, 39, 611.
(29) 9-Phenanthrol when combined with methanol and concd sul-
furic acid had previously been found to give 9-methoxyphenanthrene,
but the reaction, which was modeled on Gattermann’s,8b was carried
out at 120-130 °C. See: J app, F. R.; Findlay, A. J . Chem. Soc. 1897,
71, 1115.
(26) After being combined with methanolic HCl at 60 °C, 6-Ethoxy-
naphthalene-1,4-diol gave 10% of the 1,4-dimethoxylated naphthalene.
6,7-Diethoxy- and 6,7-dimethyl-naphthalene-1,4-diols gave 28% and
32%, respectively.

810 J . Org. Chem., Vol. 65, No. 3, 2000
Dreher et al.
3.66), 490 nm (3.52). Anal. Calcd for C44H52O6Si2: C, 72.09;
H, 7.15. Found: C, 71.86; H, 7.18.
Sch em e 5
Red u ction of Bisqu in on es. P r oced u r e A. Water (twice
the volume of the organics), followed by Na2S2O4 (25 mol/mol
helicene), was added to the helicenebisquinone dissolved in
3:1 EtOAc-CH2Cl2 (0.07 M). The solution was shaken by
means of a mechanical shaker until it was yellow (ap-
proximately 1 h), then poured into a separatory funnel, and
the aqueous layer was removed. The organics were washed
once with brine and dried (Na2SO4). The solvent was evapo-
rated. The Russig-Laatsch procedure (procedure C) was
applied immediately to the resulting moderately air-sensitive
bishydroquinones.
P r oced u r e B. Acetone (0.02 M) and AcOH (10 mol/mol
helicene) were added to the helicenebisquinone and Zn dust
(25 mol/mol helicene), and the mixture was stirred under N2
until it was yellow (10-15 min). The Zn was removed by
filtration through Celite, and the Celite was washed with CH2-
Cl2. The organics were washed with H2O (3×) and dried (Na2-
SO4), and the solvent was evaporated. The Russig-Laatsch
procedure (procedure C) was applied immediately to the
resulting moderately air-sensitive bishydroquinones.
Ru ssig-La a tsch P r oced u r e. P r oced u r e C. Saturated
HCl solutions were prepared by bubbling HCl gas into ice-
cooled alcohols. The solutions were stored at 4 °C until they
were used. The substrate was dissolved in 1,2-dichloroethane,
the HCl solution of the desired alcohol was added, and the
solution under N2 and at 60 °C was stirred for 2 h (unless
otherwise noted). The reaction mixtures were worked up by
pouring them into EtOAc, washing them with H2O, drying
them (Na2SO4), and evaporating the solvent.
synthesize a variety of structures related to those recently
arduously prepared and found to self-organize into helical
columnar assemblies with significant properties.2
Exp er im en ta l Section
THF was distilled from Na/Ph2CO; (ClCH2)2, CH2Cl2, and
Et3N from CaH2. 1,4-Benzoquinone (Aldrich, 98%) was purified
by slurrying it in CH2Cl2 with two times its weight of basic
alumina, filtering through Celite, and drying under vacuum.
Unless otherwise specified, “chromatography” refers to “flash
chromatography”.30 Na2S2O4 (tech, 85%), benzeneseleninic
anhydride (70%), and ammonium cerium(IV) nitrate (98.5%)
were purchased from Aldrich, triisopropylsilyl triflate from
GFS. (1S)-(-)-camphanoyl chloride was synthesized.31 The
matrix for FAB mass spectra was m-nitrobenzyl alcohol to
which KOAc was sometimes added.
Helicen ebisqu in on e 7 (R1 ) TIP S). Triisopropylsilyl
triflate (64.4 g, 0.21 mol, 56.5 mL) was added under N2 to a
solution, cooled in an ice bath, of 2,7-diacetylnaphthalene (21.2
g, 0.1 mol) and Et3N (84 mL) in CH2Cl2 (300 mL). After 10
min the ice bath was removed, and the mixture was stirred
for 1 h. The mixture was washed with saturated aqueous
NaHCO3 and dried (K2CO3), and the solvents were evaporated.
The residue, dissolved in 1:1 hexane-benzene + 3% triethyl-
amine, was quickly chromatographed on a plug of neutral
alumina (1.5 in d × 4 in h), eluting with this same solvent.
The product in vacuo (0.1 mm) was heated at 130 °C for 4 h,
affording 52.1 g (99%) of 2,7-bis[1-(triisopropylsiloxy)ethenyl]-
naphthalene, a pale orange oil. 1H NMR (acetone-d6, 400
MHz): δ 8.24 (d, 2 H, 0.6 Hz), 7.82 (m, 4 H), 5.16 (d, 2 H, 2.0
Hz), 4.59 (d, 2 H, 2.0 Hz), 1.39 (m, 6 H), 1.18 ppm (d, 36 H,
7.1 Hz). 13C NMR (acetone-d6, 75 MHz): δ 156.5, 136.1, 134.0,
133.8, 128.2, 125.5, 124.5, 91.5, 18.5, 13.5 ppm.
9 (R1 ) R2 ) Et). 7 (R1 ) Me, 0.20 g, 0.47 mmol), when
reduced according to procedure A, gave 8 (R1 ) Me), a yellow
solid, which was subjected to procedure C (2.0 mL of 1,2-
dichloroethane, 8.0 mL of EtOH). Elution from a short column
of silica gel, first with 10% EtOAc-hexanes and then with 50%
EtOAc-hexanes, gave 0.24 g (95% yield) of bright yellow 9
(R1 ) R2 ) Et). Mp: 218-220 °C. IR (CCl4): 3563, 2981, 1617,
1602 cm-1 1H NMR (CDCl3, 300 MHz): δ 8.57 (d, 2 H, 8.4
.
Hz), 8.07 (d, 2 H, 8.4 Hz), 7.66 (s, 2 H), 6.56 (d, 2 H, 8.4 Hz),
5.93 (d, 2 H, 8.4 Hz), 4.46 (m, 2 H), 4.35 (m, 2 H), 4.20 (m, 2
H), 4.08 (m, 2 H), 3.47 (s, 2 H), 1.64 (t, 6 H, 6.9 Hz), 1.52 ppm
(t, 2 H, 6.9 Hz). 13C NMR (CDCl3, 75 MHz): δ 152.2, 147.7,
145.8, 131.6, 126.3, 125.8, 125.4, 124.9, 121.7, 120.9, 116.0,
109.1, 108.5, 98.7, 65.1, 64.0, 15.1, 14.9 ppm. HRMS (FAB):
m/z calcd for C34H32O8 536.2199, found 536.2211.
9 (R1 ) Me, R2 ) Et). 7 (R1 ) Me, 0.16 g, 0.36 mmol), when
reduced according to procedure A, gave 8 (R1 ) Me), a yellow
solid, which was subjected to procedure C (1.2 mL of 1,2-
dichloroethane, 6.0 mL of EtOH). However, the reaction
temperature was 25 °C and the reaction time 5 min. Elution
from a short column of silica gel, first with 10% EtOAc-
hexanes and then with 50% EtOAc-hexanes, gave 0.16 g (89%
yield) of bright yellow 9 (R1 ) Me, R2 ) Et). Mp: >250 ° C. IR
(CCl4): 3564, 2973, 2936 cm-1. 1H NMR (CDCl3, 300 MHz): δ
8.57 (d, 2 H, 8.4 Hz), 8.15(d, 2 H, 8.4 Hz), 7.71 (s, 2 H), 6.60
(d, 2 H, 8.5 Hz), 5.97 (d, 2 H, 8.5 Hz), 4.25 (m, 2 H), 4.21 (s, 6
H), 4.13 (m, 2 H), 1.54 ppm (s, 6H). 13C NMR (CDCl3, 75 MHz):
δ 152.9, 147.7, 145.7, 131.6, 126.5, 125.7, 125.3, 125.0, 121.7,
120.9, 116.1, 109.0, 108.5, 98.0, 65.0, 55.8, 15.1 ppm. HRMS
(FAB): m/z calcd for C32H28O6 508.1886, found 508.1879.
9 (R1 ) R2 ) Me). When reduced according to procedure A,
7 (R1 ) TIPS, 15.0 g, 20.5 mmol) gave 8 (R1 ) TIPS), a yellow
solid, which was subjected to procedure C (83 mL of 1,2-
dichloroethane, 330 mL of MeOH). This afforded a yellow
sludge, which was mixed with EtOAc (50 mL) and hexane (250
mL), chromatographed on a plug of silica gel (3 in d × 1.5 in
h), eluting first with 5:1 hexanes-EtOAc (300 mL) and then
with EtOAc (1 L). The solvent was evaporated. Drying in vacuo
(0.1 mm) afforded 10.2 g (104%) of 9 (R1 ) R2 ) Me), a yellow
solid, which, although it contained a small amount of impurity,
was used in the resolution step. A similar experiment, using
0.70 g of 7 (R1 ) TIPS) under the same conditions, gave 0.42
g (92%) of essentially pure material. This was further purified
by means of silica gel chromatography. Mp: >240 ° C. IR
This oil (52.1 g, 99.4 mmol) under N2, in a flask fitted with
a bulb to trap small amounts of benzoquinone that sublimed
and then a reflux condenser, was heated at 120 °C for 3 days
with 1,4-benzoquinone (161.2 g, 1.42 mol) in heptane (900 mL).
The mixture was cooled to room temperature and filtered
through Celite, which was washed with hexane (ca. 1 L) until
the filtrate was no longer red. The solvents were evaporated,
and the residue was dissolved in CH2Cl2 (100 mL), loaded onto
a plug of silica gel (4 in d × 2.5 in h), and eluted with 1:1
CH2Cl2-hexane. The solvents were evaporated, the crude
product was divided into halves, and each was chromato-
graphed on silica gel (5 in d × 8 in h), eluting with CH2Cl2.
The solvent was evaporated, and the residue was shaken with
5:1 MeOH-H2O (240 mL). The solid was filtered and washed
with 5:1 MeOH-H2O (300 mL) and MeOH (40 mL). Drying in
vacuo (0.1 mm) at 90 °C for 12 h afforded 22.19 g (31%) of 7,
a bright orange powder. Mp: >250 °C. IR (CCl4): 2948, 2864,
1
1664, 1511 cm-1. H NMR (CDCl3, 400 MHz): δ 8.42 (d, 2 H,
8.6 Hz), 7.95 (d, 2 H, 8.6 Hz), 7.54 (s, 2 H), 6.76 (d, 2 H, 10.1
Hz), 6.63 (d, 2 H, 10.1 Hz), 1.53 (m, 6 H), 1.23 ppm (m, 36 H).
13C NMR (CDCl3, 75 MHz): δ 185.1, 156.7, 140.3, 135.5, 133.4,
133.0, 131.9, 129.8, 128.5, 127.2, 126.6, 122.6, 109.3, 18.1, 13.0
ppm. UV-vis (CH3CN, c ) 4.2 × 10-5 M): λmax (log ꢀ) 244
(4.59), 278 (4.35), 299 (4.51), 340 (3.91), 366 (4.02), 423 (sh,
(30) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.
(31) Gerlach, H.; Kappes, D.; Boeckman, R. K.; Maw, G. N. Organic
Syntheses 1993, 71, 48.

Alkoxyls on the Periphery of Helicenes
J . Org. Chem., Vol. 65, No. 3, 2000 811
1
(CCl4): 3568, 2938 cm-1. H NMR (CDCl3, 300 MHz): δ 8.53
Hz), 8.12 (d, 2 H, 8.1 Hz), 8.06 (d, 2 H, 8.1 Hz), 7.92 (d, 2 H,
8.7 Hz), 6.62 (d, 2 H, 8.5 Hz), 6.11 (d, 2 H, 8.5 Hz), 3.98 ppm
(s, 6 H), 3.41 ppm (s, 2 H). 13C NMR (CDCl3, 75 MHz): δ 149.6,
145.4, 131.4, 126.9 (two peaks), 125.4, 124.6, 123.1, 122.3,
119.8, 111.0, 106.9, 56.4 ppm. HRMS (FAB): m/z calcd for
(d, 2 H, 8.4 Hz), 8.08 (d, 2 H, 8.4 Hz), 7.66 (s, 2 H), 6.56 (d, 2
H, 8.5 Hz), 5.95 (d, 2 H, 8.5 Hz), 4.17 (s, 6 H), 3.95 (s, 6 H),
3.44 ppm (br s, 2H). 13C NMR (CDCl3, 75 MHz): δ 153.0, 148.5,
145.6, 131.6, 126.5, 125.7, 125.0, 124.8, 121.8, 120.8, 116.1,
108.4, 107.1, 97.9, 56.3, 55.9 ppm. HRMS (FAB): m/z calcd
for C30H24O6 480.1573, found 480.1560.
C
28H20O4 420.1362, found 420.1373.
9-Eth oxyph en an th r en e fr om 9-P h en an th r ol. Tech grade
9 (R1 ) R2 ) Et). Procedure A applied to 7 (R1 ) TIPS,
0.25 g, 0.34 mmol) gave 8 (R1 ) TIPS), which was subjected
to procedure C (1.4 mL of 1,2-dichloroethane, 5.4 mL of EtOH).
Elution from a short column of silica gel, first with 10%
EtOAc-hexanes and then with 50% EtOAc-hexanes, gave
0.17 g (93% yield) of bright yellow 9 (R1 ) R2 ) Et), mp 218-
9-phenanthrol (0.20 g, 1.0 mmol), dissolved in 1,2-dichloro-
ethane (4.2 mL), was heated with EtOH-HCl (16.8 mL) for 2
h at 60 °C and worked up, according to procedure C. The crude
product, a white solid, was chromatographed, giving 0.16 g of
9-ethoxyphenanthrene (82% yield, assuming 9-phenanthrol to
1
be 85% pure). Mp: 103-104 °C. H NMR (CDCl3, 300 MHz):
1
220 °C. Its H and 13C NMR spectra were identical to those of
δ 8.63 (d, 1 H, 7.8 Hz), 8.56 (d, 1 H, 7.5 Hz), 8.40 (d, 1 H, 7.7
Hz), 7.74 (m, 1 H), 7.63 (m, 2 H), 7.49 (m, 2 H), 6.95 (s, 1 H),
4.28 (q, 7.0 Hz, 2 H), 1.58 ppm (t, 7.0 Hz, 3 H).32 13C NMR
(CDCl3, 75 MHz): δ 152.8, 133.0, 131.2, 127.2, 127.0, 126.8,
126.3, 124.1, 122.6, 122.4, 102.5, 63.5, 14.8 ppm.
the sample prepared above 7 (R1 ) Me).
9 (R1 ) R2 ) n -Bu ). Procedure A applied to 7 (R1 ) TIPS,
0.25 g, 0.34 mmol) gave 8 (R1 ) TIPS), which was subjected
to procedure C (1.4 mL of 1,2-dichloroethane, 5.4 mL of BuOH).
Elution from a short column of silica gel, first with 10%
EtOAc-hexanes and then with 50% EtOAc-hexanes, gave
0.20 g (90% yield) of 9 (R1 ) R2 ) n-Bu), a bright yellow oily
9-Meth oxyph en an th r en e fr om 9-Eth oxyph en an th r en e.
9-Ethoxy-phenanthrene (0.10 g, 0.45 mmol), dissolved in 1,2-
dichloroethane (1.8 mL), was heated with MeOH-HCl (7.2
mL) for 2 h at 60 °C and worked up according to procedure C.
Obtained was a while solid, which was highly pure 9-meth-
oxyphenanthrene (0.94 g, 100% yield). Mp: 94-95 °C. 1H NMR
(CDCl3, 300 MHz): δ 8.63 (d, 1 H, 7.8 Hz), 8.56 (d, 1 H, 7.5
Hz), 8.40 (d, 1 H, 7.7 Hz), 7.73 (d, 1 H, 9.0 Hz), 7.63 (m, 2 H),
7.49 (m, 2 H), 6.95 (s, 1 H), 4.05 pm (s, 3 H). 13C NMR (CDCl3,
75 MHz): δ 153.5, 132.9, 131.2, 127.2, 127.0, 126.8, 126.5,
126.4, 126.3, 124.1, 122.4, 101.8, 55.3 ppm.33
Attem p ted Rea ction s of 1- a n d 2-Na p h th ols a n d of 1-
a n d 2-Meth oxyn a p h th a len es w ith EtOH. These experi-
ments were conducted according to procedure C on a 1 mmol
scale, using 16 mL of an HCl-saturated solution of EtOH and
4 mL of 1,2-dichloroethane. After 2 h at 60 °C, no changes in
the starting materials could be detected.
1
wax. IR (CCl4): 3565, 2962, 2931, 1661, 1600 cm-1. H NMR
(CDCl3, 300 MHz): δ 8.58 (d, 2 H, 8.4 Hz), 8.10 (d, 2 H, 8.5
Hz), 7.68 (s, 2 H), 6.59 (d, 2 H, 8.5 Hz), 5.95 (d, 2 H, 8.5 Hz),
4.40 (m, 2 H), 4.31 (m, 2 H), 4.20 (m, 2 H), 3.47 (s, 2 H), 2.02
(m, 4 H), 1.91 (m, 4 H), 1.68 (m, 8 H), 1.07 ppm (m, 12 H). 13
C
NMR (CDCl3, 75 MHz): δ 152.2, 147.7, 145.7, 131.5, 126.2,
125.8, 125.4, 124.9, 121.7, 120.8, 116.0, 109.0, 108.4, 98.6, 69.3,
68.0, 31.5, 31.3, 19.6, 19.5, 14.0 ppm. HRMS (FAB): m/z calcd
for C42H48O6 648.3451, found 648.3452.
9 (R1 ) R2 ) Dod ecyl). Procedure A applied to 7 (R1
)
TIPS, 0.20 g, 0.47 mmol) gave 8 (R1 ) TIPS), which was
subjected to procedure C (0.40 mL of 1,2-dichloroethane, 0.23
mL of EtOH). To remove excess dodecanol, the product was
shaken with 15 mL of MeOH, and the resulting yellow solid
was filtered on Celite, washed with MeOH, and removed from
the Celite by means of CH2Cl2, which was then evaporated.
The MeOH wash was repeated. The solids were evacuated (0.1
mm) overnight, giving 0.060 g (80% yield) of bright yellow 9
(R1 ) R2 ) dodecyl). Mp: 98-100 °C. IR (CCl4): 3562, 2928,
(P )-(+)- a n d (M)-(-)-10. Slightly impure 9 (R1 ) R2 ) Me,
10.20 g, 20.5 mmol) was refluxed for 1 h with (1S)-(-)-
camphanoyl chloride (13.3 g, 61.5 mmol), DMAP (2.5 g, 20.5
mmol), and Et3N (45 mL) in 1,2-dichloroethane (300 mL). The
solution was poured into 5:1 H2O-AcOH (1 L), and 100 mL of
brine was added. Extraction with EtOAc, washing with 10:1
H2O-AcOH, H2O, and saturated NaHCO3, drying (Na2SO4),
evaporation, and drying in vacuo (0.1 mm) at 90 °C for 2 h,
gave a yellow-orange material, which was shaken for 15 min
with 100 mL of hexane. The liquid was decanted, and the
residue was shaken vigorously for 30 min with 400 mL of 8:1
hexanes-Et2O and 50 g of sand. Filtration through Celite,
washing with hexane (100 mL), removal of the product from
the Celite with CH2Cl2, addition of cyclohexane (100 mL),
evaporation of the solvents, and drying in vacuo at 90 °C for
2 h gave a solid, which was dissolved in boiling EtOAc (1 L).
Cyclohexane (900 mL) was added, and the mixture was
allowed to stand at room temperature for 3 days. The precipi-
tate was filtered, washed with 2:1 cyclohexanes-EtOAc (150
mL), and dried overnight in vacuo (0.1 mm) at 100 °C. This
afforded 5.67 g (66%) of (P)-(+)-10.
2856 cm-1 1H NMR (CDCl3, 400 MHz): δ 8.59 (d, 2 H, 8.4
.
Hz), 8.12 (d, 2 H, 8.5 Hz), 7.69 (s, 2 H), 6.58 (d, 2 H, 8.5 Hz),
5.95 (d, 2 H, 8.5 Hz), 4.40 (m, 2 H), 4.30 (m, 2 H), 4.17 (m, 2
H), 4.00 (m, 2 H), 3.43 (s, 2H), 2.03 (m, 4 H), 1.91 (m, 4 H),
1.65 (m, 8 H), 1.28 (m, 66 H), 0.88, ppm (m, 13 H). 13C NMR
(CDCl3, 75 MHz): δ 152.3, 147.9, 145.7, 131.6, 126.4, 125.9,
125.5, 124.9, 121.7, 121.0, 116.0, 109.1, 108.5, 98.7, 69.7, 68.4,
31.9, 29.7, 29.6, 29.4, 26.4, 22.7, 14.1 ppm. HRMS (FAB): m/z
calcd for C74H112O6 1096.8459, found 1096.8463.
P r ep a r a tion of [7]Helicen e 13. Procedure B was applied
to 12 (1.0 g, 0.85 mmol), and the resulting yellow solid was
subjected to procedure C (1.9 mL of 1,2-dichloroethane, 1.9 mL
of dodecanol). The yield of yellow-brown oily solid 13, which
after trituration with MeOH (30 mL), as described above for
9 (R1 ) R2 ) dodecyl), was very pure, was 1.20 g (97% yield).
IR (CCl4): 3561, 2902, 2852 cm-1 1H NMR (CDCl3, 400
.
MHz): δ 8.51 (d, 2 H, 8.7 Hz), 8.42 (d, 2 H, 8.7 Hz), 7.14 (s, 2
H), 6.31 (d, 2 H, 8.5 Hz), 5.88 (d, 2 H, 8.5 Hz), 4.47 (m, 2 H),
4.30 (m, 4 H), 4.16 (m, 2 H), 3.92 (m, 4 H), 3.48 (s, 3 H), 2.00
(m, 9 H), 1.88 (m, 2 H), 1.63 (m, 8 H), 1.29 (m, 111 H), 0.89
ppm (m, 21 H). 13C NMR (CDCl3, 75 MHz): δ 152.0, 147.5,
143.9, 143.4, 128.0, 126.3, 124.4, 124.0, 122.1, 121.4, 120.1,
117.7, 109.3, 106.9, 98.4, 74.1, 69.0, 68.4, 32.0, 30.6, 29.7, 29.4,
26.6, 26.4, 26.3, 22.7, 14.1 ppm. HRMS (FAB): m/z calcd for
Evaporating the solvent from the filtrate gave a solid, which
was dissolved in EtOAc (100 mL), and hexane (150 mL) was
added. The suspension was chromatographed on a plug of silica
gel (3.5 in d × 1.8 in h), eluting with 12 portions of 3:2
hexanes-EtOAc (100 mL each). The resulting solid was boiled
in 20:1 cyclohexanes-EtOAc (200 mL), and after the mixture
had cooled to room temperature, was filtered and dried in
vacuo (0.1 mm), affording 5.31 g (62%) of (M)-(-)-10. The
silica gel plug was washed with 1:1 CH2Cl2-EtOAc, and after
the solvent had been evaporated, the residue was chromato-
graphed, eluting with 1:1 hexanes-EtOAc. This afforded an
additional 0.66 g (8%) of (M)-(-)-10. The later fractions,
containing (P)-(+)-10, were dissolved in 20 mL of boiling
EtOAc, and after 10 mL of cyclohexane had been added, cooling
C
102H162O8 1515.2270, found 1515.2286.
9 (R1O ) H, R2 ) Me). When reduced according to
procedure A, 7 (R1 ) H, 25 mg, 0.064 mmol) gave 8 (R1O ) H,
R2 ) H), a yellow solid, which was subjected to procedure C
(0.26 mL of 1,2-dichloroethane, 1.1 mL of MeOH). The 1H NMR
spectrum of the crude material showed <2% of any compounds
to be present in which 9 is methylated at the inside position
(OMe in place of 9's OH). Elution with CH2Cl2 from a short
column of silica gel gave 0.023 g (85% yield) of bright yellow
solid 9 (R1O ) H, R2 ) Me). Mp: 213-215 °C. IR (CCl4): 3564,
(32) The melting point and 1H NMRs match those published. Muller,
P.; Pautex, N. Helv. Chim. Acta 1988, 71, 1630.
(33) The melting point and 1H and 13C NMRs match those published.
Stuhr-Hansen, N.; Henriksen, L. Synth. Commun. 1997, 27, 89.
2933 cm-1 1H NMR (CDCl3, 300 MHz): δ 8.43 (d, 2 H, 8.7
.

812 J . Org. Chem., Vol. 65, No. 3, 2000
Dreher et al.
to room temperature gave a precipitate that was dried in vacuo
at 90 °C. An additional 0.74 g (9%) of (P)-(+)-10 was obtained.
(M)-(-)-10. Mp: >250 °C. [R]D: -1410 (c 0.020, CH3CN).
54.2, 31.9, 30.7, 29.7, 29.5, 29.4, 28.7, 28.4, 26.5, 26.4, 26.3,
22.7, 16.8, 16.6, 14.1, 9.5 ppm. UV-vis (hexane, c ) 3.0 × 10-5
M): λmax (log ꢀ) 234 (4.40), 254 (4.46), 268 (4.41), 284 (4.46),
320 (sh, 4.34), 388 nm (sh, 3.78). CD (c ) 3.0 × 10-5 M,
hexane), nm (∆ꢀ): 223 (sh, 44), 240 (162), 261, (-31), 268
(-23), 290 (-110), 317 (sh, -67), 373 (92), 399 (sh, 54). HRMS
IR (CCl4): 2973, 1790, 1747 cm-1 1H NMR (CDCl3, 400
.
MHz): δ 8.45 (d, 2 H, 8.4 Hz), 7.96 (d, 2 H, 8.5 Hz), 7.70 (s, 2
H), 6.54 (d, 2 H, 8.4 Hz), 6.05 (d, 2 H, 8.4 Hz), 4.23 (s, 6 H),
4.02 (s, 6 H), 1.52 (m, 2 H), 1.42 (m, 2 H), 1.15 (m, 2 H), 0.92
(s, 6 H), 0.80 (m, 2 H), 0.57 (s, 6 H), 0.43 ppm (s, 6 H). 13C
NMR (CDCl3, 75 MHz): δ 178.2, 165.5, 154.0, 152.9, 140.3,
130.7, 126.2, 126.0 (2 peaks), 120.7, 120.1, 113.9, 105.0, 98.2,
89.5, 56.1, 55.8, 54.5, 54.2, 29.3, 28.8, 16.2, 16.1, 9.5 ppm. UV-
vis (CH3CN, c ) 3.6 × 10-5 M): λmax (log ꢀ) 225 (4.28), 254
(4.51), 263 (sh, 4.50), 283 (sh, 4.39), 309 (4.20), 314 (sh, 4.33),
327 (4.44), 351 (sh, 4.03), 407 (3.46), 432 nm (3.46). CD (c )
3.6 × 10-5 M, CH3CN), nm (∆ꢀ): 229 (-27), 251 (122), 261
(sh, 85), 280 (sh, 9), 299 (-40), 314 (-3), 323 (-0.3), 344 (-97),
364 (sh, -81), 431 (11). Anal. Calcd for C50H48O12: C, 71.42;
H, 5.75. Found C, 71.41; H, 5.73.
(FAB): m/z + K calcd for
C122H186O14 1914.3480, found
1914.3400.
(M)-(-)-13-Dica m p h a n a te. [R]D: -920 (c 0.016, hexane).
IR (CCl4): 2967, 2909, 2852, 1793, 1743 cm-1. 1H NMR (CDCl3,
400 MHz): δ 8.42 (d, 2 H, 8.7 Hz), 8.35 (d, 2 H, 8.7 Hz), 7.05
(s, 2 H), 6.27 (d, 2 H, 8.5 Hz), 5.94 (d, 2 H, 8.5 Hz), 4.32 (m, 4
H), 4.15 (m, 2 H), 4.06 (m, 4 H), 3.90 (m, 2 H), 2.00 (m, 12 H),
1.58 (m, 12 H), 1.29 (m, 103 H), 0.97 (m, 2 H), 0.92 (s, 2 H),
0.90 (m, 26 H), 0.57 (s, 6 H), 0.41 ppm (s, 6 H). 13C NMR
(CDCl3, 75 MHz): δ 177.7, 165.8, 153.3, 151.6, 143.5, 138.2,
127.7, 127.0, 125.1, 124.2, 122.4, 122.0, 121.4, 120.8, 114.8,
103.9, 97.5, 89.5, 73.9, 68.4, 68.2, 54.1 (2 peaks), 53.3, 31.9,
30.7, 29.7, 29.5, 29.3, 28.5, 26.5, 26.4, 26.3, 22.6, 16.1, 16.0,
14.1, 9.4 ppm. UV-vis (hexane, c ) 2.9 × 10-5 M): λmax (log ꢀ)
232 (4.42), 254 (4.47), 265 (4.44), 283 (4.50), 320 (sh, 4.37),
388 nm (sh, 3.80). CD (c ) 2.9 × 10-5 M, hexane), nm (∆ꢀ):
219 (sh, -62), 237 (-218), 261 (sh, 15), 286 (169), 315 (92),
373 (-115), 396 (sh, -82). HRMS (FAB): m/z + K calcd for
(P )-(+)-10. Mp: >250 °C. [R]D: +1120 (c 0.020, CH3CN).
IR (CCl4): 2965, 2940, 1797, 1764 cm-1. 1H NMR (CDCl3, 400
MHz): δ 8.43 (d, 2 H, 8.4 Hz), 7.98 (d, 2 H, 8.5 Hz), 7.57 (s, 2
H), 6.53 (d, 2 H, 8.4 Hz), 5.94 (d, 2 H, 8.4 Hz), 4.19 (s, 6 H),
4.01 (s, 6 H), 1.63 (m, 2 H), 1.46 (m, 4 H), 1.15 (m, 2 H), 0.94
(s, 6 H), 0.67 (s, 6 H), 0.25 ppm (s, 6 H). 13C NMR (CDCl3, 75
MHz): δ 177.5, 165.8, 154.1, 153.0, 140.6, 131.4, 127.0, 126.6,
125.5, 125.4, 124.7, 121.0, 120.7, 114.6, 105.0, 97.5, 90.2, 56.1,
55.9, 54.3, 53.9, 29.1, 28.9, 16.6, 16.1, 9.5 ppm. UV-vis
(hexane, c ) 3.0 × 10-5 M): λmax (log ꢀ) 225 (4.18), 253 (4.46),
263 (sh, 4.44), 283 (sh, 4.32), 326 (4.35), 344 (sh, 3.94), 431
nm (3.31). CD (c ) 3.0 × 10-5 M, CH3CN), nm (∆ꢀ): 231 (44),
252 (-121), 263 (sh, -92), 281 (sh, -20), 299 (19), 323 (-20),
344 (91), 360 (sh, 78), 431 (-8). HRMS (FAB): m/z calcd for
C
122H186O14 1914.3480, found 1914.3514.
(P )-(+)-13. A flask containing (P)-(+)-13-d ica m p h a n a te
(0.56 g, 0.30 mmol) was evacuated and filled with N2 three
times, and MeLi in Et2O (2.2 mL, 1.6 M, 3.5 mmol) was added.
After the mixture had stirred for 1 h at 25 °C (turning deep
red in the process), the reaction was quenched by the addition
of saturated aqueous NH4Cl, whereupon the color turned
yellow. Addition of H2O, extraction with EtOAc, washing with
brine, drying (Na2SO4), evaporation, and chromatography
(eluent: CH2Cl2) gave 0.44 g (97% yield) of (P)-(+)-13, an oil.
[R]D: +690 (c 0.016, hexane). The 1H NMR and 13C NMR
spectra of (P)-(+)-13 were identical to that of the racemic
material. UV-vis (hexane, c ) 3.5 × 10-5 M): λmax (log ꢀ) 215
(4.41), 233 (4.33), 255 (4.43), 288 (4.31), 309 (4.38), 375 nm
(sh, 3.95). CD (c ) 3.5 × 10-5 M, hexane), nm (∆ꢀ): 233 (98),
250 (sh, 31), 273 (-116), 305 (-76), 343 (sh, 49), 370 (67), 424
(sh, 27).
C
50H48O12 840.3146, found 840.3162.
(M)-(-)- a n d (P )-(+)-9 (R1 ) R2 ) Me). A flask containing
(M)-(-)-10 (2.1 g, 2.5 mmol) and KOH (5.6 g, 0.1 mol) was
evacuated and filled with N2 three times. EtOH (30 mL),
previously degassed by boiling under N2, was added by syringe.
After the mixture had stirred for 1 h at 25 °C (during which
time it turned deep red), aqueous HCl was added, whereupon
the color turned to yellow. Addition of H2O, extraction with
EtOAc, washing with brine, drying (Na2SO4), evaporation, and
chromatography (eluents: CH2Cl2 to 30:1 CH2Cl2-EtOAc)
gave 1.1 g (93% yield) of (M)-(-)-9 (R1 ) R2 ) Me). The same
procedure applied to (P)-(+)-10 gave 1.2 g (99% yield) of (P)-
(+)-9 (R1 ) R2 ) Me). Mp: 158-160 °C. [R]D: +2030 (c 0.010,
P r ep a r a tion of Op tica lly Active Ru ssig-La a tsch P r od -
u cts. P r oced u r e D. After an HCl-saturated solution of the
alcohol had been added to a resolved Russig-Laatsch product,
the solution was heated at the specified temperature for 2 h.
A Hickman distillation head that was attached to the flask
trapped the methanol that formed. The reaction mixture was
poured into EtOAc, which was then washed with water, dried
(Na2SO4), and evaporated.
1
CH3CN). The H NMR and 13C NMR spectra of (M)-(-)-9 and
(P)-(+)-9 (R1 ) R2 ) Me) were identical to that of the racemic
material. UV-vis of (M)-(-)-9 (R1 ) R2 ) Me, in CH3CN, c )
3.2 × 10-5 M): λmax (log ꢀ) 239 (4.67), 258 (sh, 4.51), 271 (4.34),
291 (4.39), 303 (4.33), 321 (4.40), 369 (3.94), 430 nm (3.32).
CD of (M)-(-)-9 (R1 ) R2 ) Me, in CH3CN, c ) 3.2 × 10-5 M),
nm (∆ꢀ): 238 (-44), 257 (sh, -13), 263 (-7), 272 (sh, -10),
291 (-41), 307 (-67), 317 (-13), 350 (128), 396 (sh, 11), 439
(-4).
(M)-(-)-9 (R1 ) R2 ) Et). (M)-(-)-9 (R1 ) R2 ) Me, 0.10 g,
0.21 mmol) was heated at 75 °C with EtOH-HCl (1.0 mL) and
worked up according to procedure D. Elution by CH2Cl2 from
a short column of silica gel gave 0.10 g (93% yield) of (M)-
(-)-9 (R1 ) R2 ) Et), a bright yellow solid. Mp: 114-116 °C.
[R]D: -1700 (c 0.011, CH3CN). The 1H NMR and 13C NMR
spectra were identical to those of the racemic material,
prepared above from 7 (R1 ) Me) and from 7 (R1 ) TIPS). UV-
vis (CH3CN, c ) 4.2 × 10-5 M): λmax (log ꢀ) 240 (4.40), 259
(4.35), 273 (4.24), 291 (4.28), 305 (4.22), 323 (4.28) 344 (sh,
4.03), 430 nm (sh, 3.29). CD (c ) 4.2 × 10-5 M, CH3CN), nm
(∆ꢀ): 239 (38), 254 (15), 263 (7), 270 (sh, 11), 292 (40), 308
(10), 315 (16), 350 (-117), 439 (4).
Th e (P )-(+)- a n d (M)-(-)-Dica m p h a n a tes of 13. A solu-
tion of 13 (1.2 g, 0.79 mmol), (1S)-(-)-camphanoyl chloride
(0.51 g, 2.37 mmol), DMAP (0.096 g, 0.79 mmol), and Et3N
(2.7 mL) in 1,2-dichloroethane (30 mL) was refluxed for 2 h.
The cooled reaction mixture was poured into 1 M HCl, and
after the organic layer had been washed with H2O, saturated
aqueous NaHCO3, and H2O, dried (Na2SO4), and freed of
solvent, the diastereomers were separated by silica gel chro-
matography (eluents from hexanes to CH2Cl2). Obtained were
0.65 g (88% yield) of oily (P)-(+)-13-dicamphanate and 0.54 g
(73% yield) of (M)-(-)-13-dicamphanate.
(M)-(-)-9 (R1 ) R2 ) n -Bu ). (M)-(-)-9 (R1 ) R2 ) Me, 0.10
g, 0.21 mmol) was heated with HCl in BuOH (0.95 mL) at 90
°C and worked up according to procedure D. Elution by
hexanes, then CH2Cl2, from a short plug of silica gel gave 0.12
g (91% yield) of (M)-(-)-9 (R1 ) R2 ) n-Bu), a bright yellow
(P )-(+)-13-d ica m p h a n a te. [R]D: +550 (c 0.016, hexane). IR
1
(CCl4): 2967, 2902, 2852, 1796, 1778 cm-1. H NMR (CDCl3,
1
400 MHz): δ 8.32 (d, 2 H, 8.7 Hz), 8.28 (d, 2 H, 8.7 Hz), 7.07
(s, 2 H), 6.31 (d, 2 H, 8.5 Hz), 5.83 (d, 2 H, 8.5 Hz), 4.31 (m, 4
H), 4.15 (m, 4 H), 4.03 (m, 2 H), 3.90 (m, 2 H), 8.32 (d, 2 H, 8.7
Hz), 1.97 (m, 13 H), 1.74 (m, 2 H), 1.60 (m, 17 H), 1.29 (m, 112
H), 1.18 (m, 2 H), 0.99 (s, 6 H), 0.90 (m, 21 H), 0.72 (s, 6 H),
0.58 ppm (s, 6 H). 13C NMR (CDCl3, 75 MHz): δ 177.4, 165.6,
153.0, 151.7, 143.6, 138.2, 128.2, 126.9, 124.9, 124.7, 123.2,
121.9, 121.0, 120.8, 115.7, 104.3, 97.7, 90.5, 74.0, 68.3, 54.4,
oily wax. [R]D: -1510 (c 0.013, CH3CN). The H NMR and 13C
NMR spectra were identical to those of the racemic material,
prepared above from 7 (R1 ) TIPS). UV-vis (CH3CN, c ) 4.0
× 10-5 M): λmax (log ꢀ) 221 (4.34), 240 (4.42), 259 (sh, 4.38),
277 (4.29), 292 (4.31), 306 (4.28), 321 (4.31), 350 (sh, 4.06),
430 nm (sh, 340). CD (c ) 4.0 × 10-5 M, CH3CN), nm (∆ꢀ):
242 (29), 254 (sh, 20), 263 (13), 271 (16), 293 (43), 307 (19),
314 (22), 351 (-114), 42 (3).

Alkoxyls on the Periphery of Helicenes
J . Org. Chem., Vol. 65, No. 3, 2000 813
(M)-(-)-9 (R1 ) R2 ) Dod ecyl). (M)-(-)-9 (R1 ) R2 ) Me,
0.11 g, 0.23 mmol) was heated with HCl in dodecanol (1.0 mL)
at 90 °C and worked up according to procedure D. The product
was triturated with MeOH (15 mL) as described above for 9
(R1 ) R2 ) dodecyl). Obtained was 0.21 g (84% yield) of (M)-
(-)-9 (R1 ) R2 ) dodecyl), a bright yellow solid. Mp: 72-74
Chromatography (eluent: CH2Cl2) provided 0.10 g (73% yield)
of (M)-(-)-7 (R1 ) dodecyl), a red wax. Mp: 208-209 °C. [R]D:
-2410 (c 0.011, CH2Cl2). IR (CCl4): 2925, 2851, 1666, 1513
cm-1. 1H NMR (CDCl3, 300 MHz): δ 8.44 (d, 2 H, 8.7 Hz), 7.95
(d, 2 H, 8.7 Hz), 7.50 (s, 2 H), 6.78 (d, 2 H, 10.1 Hz), 6.63 (d,
2 H, 10.1 Hz), 4.44 (m, 2 H), 4.33 (m, 2 H), 2.01 (m, 4 H), 1.61
(m, 4 H), 1.29 (m, 32 H), 0.89 ppm (m, 6 H). 13C NMR (CDCl3,
75 MHz): δ 185.2, 158.8, 140.2, 135.6, 133.6, 133.0, 131.2,
128.5, 127.6, 126.9, 126.4, 122.1, 102.0, 69.4, 31.9, 29.6, 29.4,
29.1, 26.2, 22.7, 14.1 ppm. UV-vis (hexane, c ) 3.5 × 10-5
M): λmax (log ꢀ) 236 (4.64), 245 (sh, 4.63), 277 (4.30), 297 (4.52),
338 (3.84), 363 (3.98), 430 nm (sh, 3.69). CD (c ) 3.5 × 10-5
M, hexane), nm (∆ꢀ): 241 (-5), 262 (-36), 297 (72), 352 (-93),
394 (-15), 433 (-21), 522 (2). HRMS (FAB): m/z calcd for
1
°C. [R]D: -770 (c 0.022, hexane). The H NMR and 13C NMR
spectra were identical to those of the racemic material,
prepared above from 7 (R1 ) TIPS). UV-vis (CH3CN, c ) 1.9
× 10-5 M): λmax (log ꢀ) 221(4.55), 243 (4.78), 260 (sh, 4.57),
278 (4.38), 293 (4.42), 306 (4.33), 328 (4.45), 355 (sh, 4.08),
389 nm (sh, 3.90). CD (c ) 1.9 × 10-5 M, CH3CN), nm (∆ꢀ):
228 (31), 238 (19), 249 (25), 264 (16), 271 (20), 278 (15), 291
(37), 316 (-13), 326 (19), 356 (-116), 446 (8).
P r ep a r a tion of Bis-p-qu in on es. P r oced u r e E. The Rus-
sig-Laatsch products, dissolved in x mL of CH2Cl2, were added
in drops during 1 h to a rapidly stirring solution at room
temperature of cerric ammonium nitrate (CAN, 10 molar
equivalents) in x mL of H2O and x mL of acetonitrile. After
this had stirred for 30 min, the mixture was poured into a
separatory funnel containing EtOAc and H2O, which was
gently swirled. (Vigorous shaking produced an emulsion.) The
organics were dried (Na2SO4), and the solvent was evaporated.
(M)-(-)-7 (R1 ) Me). Procedure E was followed, using 1.0
g (2.1 mmol) of (M)- (-)-9 (R1 ) R2 ) Me), x ) 170.
Chromatography (eluent: 20:1 CH2Cl2-EtOAc) provided 0.66
g (71% yield) of (M)-(-)-7 (R1 ) Me), a red solid. Mp: >250
°C. [R]D: -3210 (c 0.006, CH3CN). CD (c ) 2.6 × 10-5 M, CH3-
CN), nm (∆ꢀ): 226 (11), 233 (2), 236 (3), 260 (-47), 297 (66),
307 (sh, 47), 351 (-87), 395 (-11), 435 (-18).
C
50H60O6 756.4390, found 756.4421.
(P )-(+)-12. Procedure E was followed, using 0.10 g (0.067
mmol) of 13, x ) 5. Chromatography (eluent: 4:1 CH2Cl2-
hexanes) provided 0.058 g (75% yield) of (P)-(+)-12, a red-
brown wax. [R]D: +1570 (c 0.016, CH2Cl2) (lit.13b [R]D +1480 (c
0.050, CH2Cl2)). The 1H NMR and 13C NMR spectra of (P)-
(+)-12 were identical to those of the racemic material.14a
P r ep a r a tion of Bis-o-qu in on es. P r oced u r e F . A solution
of the Russig-Laatsch products in dry THF was stirred for
15 min with activated 4 Å molecular sieves in a flame-dried
flask before it was added by cannula to a solution of benzene-
selenininc anhydride (3 mol/mol helicene) in the same amount
of dry THF that had been stirred in another flame-dried flask
for 15 min with 4 Å molecular sieves. A minimal amount of
THF was used to complete the transfer. The mixture, after it
had stirred under N2 for 2 h at room temperature, was poured
into aqueous NaHCO3. The organics were washed with H2O
and dried (Na2SO4), and the solvent was evaporated.
(P )-(+)-7 (R1 ) Me). Procedure E was followed, using 1.2
g (2.4 mmol) of (P)-(+)-9 (R1 ) R2 ) Me), x ) 180. Chroma-
tography (eluent: 20:1 CH2Cl2-EtOAc) provided 0.81 g (74%
yield) of (P)-(+)-7 (R1 ) Me). [R]D: 3210 (c 0.007, CH3CN). UV-
vis (CH3CN, c ) 3.2 × 10-5 M): λmax (log ꢀ) 233 (4.66), 244 (sh,
4.64), 279 (4.33), 297 (4.49), 339 (3.86), 366 nm (3.92). CD (c
) 3.2 × 10-5 M, CH3CN), nm (∆ꢀ): 226 (-11), 234 (-2), 238
(-3), 259 (47), 297 (-64), 308 (sh, -45), 351 (85), 395 (11),
(M)-(-)-11 (R1 ) R2 ) d od ecyl). Following procedure F,
the amount of (M)-(-)-9 (R1 ) R2 ) dodecyl) was 0.10 g (0.091
mmol) and of THF 2 × 5 mL. Silica gel chromatography
(eluent: CH2Cl2) gave the red-brown product (0.070 g, 68%
yield). Mp: 62-64 °C. [R]D: -2950 (c 0.020, hexane). IR
(CCl4): 2928, 2856, 1662, 1595 cm-1 1H NMR (CDCl3, 400
.
1
435 (17). The H and 13C NMR spectra of (+)- and (-)-7 were
MHz): δ 8.29 (d, 2 H, 8.6 Hz), 7.79 (d. 2 H, 8.7 Hz), 7.32 (s, 2
H), 5.71 (s, 2 H), 4.35 (m, 2 H), 4.26 (m, 2 H), 4.17 (m, 2 H),
4.07 (m, 2H), 1.99 (m, 8 H), 1.56 (m, 73 H), 1.29 (m, 73 H),
0.88 ppm (m, 12 H). 13C NMR (CDCl3, 75 MHz): δ 182.3, 182.2,
168.2, 159.7, 135.1, 133.5, 133.1, 127.5, 125.9 (2 peaks), 125.3,
122.0, 102.3, 101.9, 70.1, 69.0, 31.9, 29.6, 29.4 (2 peaks), 29.3,
29.1, 28.4, 26.2, 26.0, 22.7, 14.1 ppm. UV-vis (CH3CN, c )
2.7 × 10-5 M): λmax (log ꢀ) 242 (4.74), 269 (4.53), 293 (4.62),
321 nm (sh, 4.33). CD (c ) 2.7 × 10-5 M, CH3CN), nm (∆ꢀ):
234 (-117), 250 (-8), 253 (-10), 300 (179), 380 (-125), 431
(sh, -35). HRMS (FAB): m/z + K calcd for C74H108O8 1163.7632,
found 1163.7681.
identical to those of the racemic material.12
(M)-(-)-7 (R1 ) Et). Procedure E was followed, using 80
mg (0.15 mmol) of (M-(-)-9 (R1 ) R2 ) Et), x ) 12. Chroma-
tography (eluent: 20:1 CH2Cl2-EtOAc) provided 53 mg (75%
yield) of (M)-(-)-7 (R1 ) Et), a red solid. Mp: >250 °C. [R]D:
-3180 (c 0.010, CH3CN). IR (CCl4) 2978, 1661, 1596, 1515
cm-1. 1H NMR (CDCl3, 300 MHz): δ 8.45 (d, 2 H, 8.7 Hz), 7.94
(d, 2 H, 8.7 Hz), 7.50 (s, 2 H), 6.77 (d, 2 H, 10.1 Hz), 6.62 (d,
2 H, 10.1 Hz), 4.49 (m, 2 H), 4.39 (m, 2 H), 1.64 ppm (m, 6 H).
13C NMR (CDCl3, 75 MHz): δ 185.1, 158.6, 140.1, 135.5, 133.6,
132.9, 131.1, 128.4, 127.5, 126.8, 126.3, 122.0, 101.9, 65.0, 14.6
ppm. UV-vis (CH3CN, c ) 2.5 × 10-5 M): λmax (log ꢀ) 236
(4.65), 243 (sh, 4.64), 281 (4.32), 298 (4.48), 340 (3.84), 363
(3.92), 426 nm (3.62). CD (c ) 2.5 × 10-5 M, CH3CN), nm
(∆ꢀ): 227 (11), 236 (sh, 1.0), 258 (-45), 297 (63), 352 (-86),
400 (-10), 435 (-18). HRMS (FAB): m/z calcd for C30H20O6
476.1260, found 476.1257.
(P )-(+)-14. Following procedure F, the amount of (P)-(+)-
13 was 0.25 g (0.16 mmol) and of THF 2 × 5 20 mL. Silica gel
chromatography (eluents: 1:1 hexane-CH2Cl2 to CH2Cl2) gave
the orange-brown waxy product, 0.16 g (64% yield). Mp: 52-
53 °C. [R]D: +2180 (c 0.14, dodecane). IR (CCl4): 2928, 2856,
1
1661, 1599 cm-1. H NMR (CDCl3, 300 MHz): δ 8.24 (s, 4 H),
(M)-(-)-7 (R1 ) n -Bu ). Procedure E was followed, using
0.11 g (0.16 mmol) of (M)-(-)-9 (R1 ) R2 ) n-Bu), x ) 13.
Chromatography (eluents from CH2Cl2 to 20:1 CH2Cl2-EtOAc)
provided 0.63 g (73% yield) of (M)-(-)-7 (R1 ) n-Bu), a red solid.
Mp: 206-207 °C. [R]D: -2930 (c 0.011, CH3CN). IR (CCl4):
7.05 (s, 2 H), 5.59 (s, 2 H), 4.37 (m, 4 H), 4.18 (m, 4 H), 4.00
(m, 4 H), 1.92 (m, 12 H), 1.56 (m, 9 H), 1.29 (m, 104 H), 0.89
ppm (m, 18 H). 13C NMR (CDCl3, 75 MHz): δ 181.1, 176.9,
168.5, 160.8, 144.8, 131.3, 130.3, 128.3, 126.2, 125.0, 124.1,
122.8, 120.7, 102.2, 100.7, 74.0, 69.9, 69.1, 31.9, 30.4, 29.6, 29.5,
29.4, 29.3, 29.1, 28.4, 26.2, 22.7, 17.7, 14.1 ppm. UV-vis
(dodecane, c ) 2.0 × 10-5 M): λmax (log ꢀ) 217 (sh, 4.42), 260
(3.67), 282 (4.45), 304 (4.50), 352 (sh, 4.55), 431 nm (3.65). CD
(c ) 2.0 × 10-5 M, dodecane), nm (∆ꢀ): 240 (35), 243 (-17),
262 (18), 300 (-139), 358 (138), 410 (12), 459 (22). HRMS
1
2965, 1665, 1595, 1515 cm-1. H NMR (CDCl3, 300 MHz): δ
8.45 (d, 2 H, 8.6 Hz), 7.96 (d, 2 H, 8.7 Hz), 7.51 (s, 2 H), 6.78
(d, 2 H, 10.2 Hz), 6.63 (d, 2 H, 10.2 Hz), 4.43 (m, 2 H), 4.34
(m, 2 H), 2.01 (m, 4 H), 1.66 (m, 4 H), 1.08 ppm (t, 6 H, 7.3
Hz). 13C NMR (CDCl3, 75 MHz): δ 185.2, 158.8, 140.2, 135.6,
133.6, 133.0, 131.2, 128.4, 127.6, 126.9, 126.3, 122.1, 101.9,
69.1, 31.1, 19.4, 13.9 ppm. UV-vis (CH3CN, c ) 3.1 × 10-5
M): λmax (log ꢀ) 235 (4.64), 246 (4.64), 280 (4.35), 298 (4.49),
341 (3.86), 367 nm (3.94). CD (c ) 3.1 × 10-5 M, CH3CN), nm
(∆ꢀ): 226 (13), 237 (sh, 1), 260 (-47), 297 (70), 351 (-89), 399
(FAB): m/z + K calcd for
1582.1489.
C102H158O10 1582.1492, found
Ack n ow led gm en t. We thank the NSF for grant
support (CHE98-02316) and Dr. Alfred Bader for a
Bader Fellowship to K.P. We are grateful to Vinka
Parmakovich and Dr. Yasuhiro Itagaki for measuring
HRMS spectra.
(-11), 437 (-17). HRMS (FAB): m/z calcd for
C34H26O6
530.1729, found 530.1723.
(M)-(-)-7 (R1 ) d od ecyl). Procedure E was followed, using
0.20 g (0.18 mmol) of (M)-(-)-9 (R1 ) R2 ) dodecyl), x ) 15.

814 J . Org. Chem., Vol. 65, No. 3, 2000
Dreher et al.
Su p p or tin g In for m a tion Ava ila ble: Graphs showing the
1H and 13C NMR and IR spectra of 7 (R1 ) TIPS), (M)-(-)-7
(R1 ) Et, n-Bu, dodecyl), 9 (R1 ) R2 ) Me, Et, n-Bu, dodecyl;
R1O ) H, R2 ) Me; R1 ) Me, R2 ) Et), (P)-(+)- and (M)-(-)-
10, (M)-(-)-11, 13, (P)-(+)- and (M)-(-)-13-dicamphanates, (M)-
(-)-14; the UV and CD spectra of (P)-(+)- and (M)-(-)-7 (R1 )
(-)-10, (M)-(-)-11, (P)-(+)-, and (M)-(-)-13, (P)-(+)- and (M)-
(-)-13-dicamphanates, (M)-(-)-14; and 1H and 13C NMR
spectra of 2,7-bis-[1-(triisopropylsiloxy)ethenyl]naphthalene.
This material is available free of charge via the Internet at
http://pubs.acs.org.
Me), (M)-(-)-7 (R1 ) Et, n-Bu, dodecyl), (P)-(+)-9 (R1 ) R2
)
Me), (M)-(-)-9 (R1 ) R2 ) Et, n-Bu, dodecyl), (P)-(+)- and (M)-
J O9914972