Binaphthalene-derived iminium salt catalysts for highly enantioselective asymmetrie epoxidation

Article abstract of DOI:10.1002/ejoc.200900252

Enantiomerically enriched epoxides are useful intermediates that have found many applications in asymmetric synthesis, and development of efficient catalysts for asymmetric epoxidation has received considerable attention, In this manuscript we describe the design, preparation, and use of new highly selective imlnium salt organocatalysts for asymmetric epoxidation, based around a chiral binaphthalene motif coupled with a chiral substituted dioxane moiety. The new catalysts have been tested in the catalytic asymmetric epoxidation of unfunctionalized alkenes, and provide up to 95 % ee.

Full text of DOI:10.1002/ejoc.200900252

FULL PAPER
DOI: 10.1002/ejoc.200900252
Binaphthalene-Derived Iminium Salt Catalysts for Highly Enantioselective
Asymmetric Epoxidation
Philip C. Bulman Page,*[a] Benjamin R. Buckley,[b] Mohamed M. Farah,[b] and
A. John Blacker[c]
Keywords: Organocatalysis / Epoxidation / Enantioselectivity / Asymmetric catalysis
Enantiomerically enriched epoxides are useful intermediates
that have found many applications in asymmetric synthesis,
and development of efficient catalysts for asymmetric epox-
idation has received considerable attention. In this manu-
script we describe the design, preparation, and use of new
highly selective iminium salt organocatalysts for asymmetric
epoxidation, based around a chiral binaphthalene motif cou-
pled with a chiral substituted dioxane moiety. The new cata-
lysts have been tested in the catalytic asymmetric epoxid-
ation of unfunctionalized alkenes, and provide up to 95% ee.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
as in 3, would bring these controlling asymmetric elements
of the catalyst nearer to the site of oxygen transfer, and
might therefore increase the ee induced in an epoxidation
reaction.[7] We[7b–7e] and others[8] have seen a certain success
with our 5-amino-2,2-dimethyl-4-phenyl-1,3-dioxane-de-
rived family of catalysts such 3–6, some of which are ex-
tremely active, with catalyst loadings as low as 0.1 mol-%,
and giving enantiomeric excesses of up to 97% in epoxid-
ation reactions.
Introduction
Enantiomerically enriched epoxides have found many ap-
plications in asymmetric synthesis,[1] and development of
efficient catalysts for asymmetric epoxidation has received
considerable attention.[2] Oxaziridinium salts such as 1, gen-
erated from iminium salts and a stoichiometric oxidant,
typically Oxone, are strong electrophilic oxidants for olefin
epoxidation,[3] and have the advantage that they are “organ-
ocatalysts,” no metal species being involved in the catalysed
reaction.
Initially, enantiomeric excesses when employing enantio-
merically pure oxaziridinium salts, for example 2, ranged
from low to moderate.[3–5] Our own approach to chiral im-
inium salt catalysts, which has led to several systems that
afford epoxides with Ͼ90% ee,[6,7d] differs from previous
investigations, where the exocyclic group attached to the ni-
trogen atom of the iminium salt has invariably been methyl
or ethyl.
Our standard conditions for the epoxidation reactions,
optimized for 1-phenylcyclohexene as substrate, comprise
typically 0.1 to 10 mol-% of the iminium salt, two equiva-
lents of Oxone, and four equivalents of sodium carbonate
in water/acetonitrile (1:1) at 0 °C. Blank reactions carried
out in parallel under the same conditions, in the presence
of Oxone, but without catalyst, gave no reaction over up to
eight hours when four equivalents of sodium carbonate
were present. Recently we have reported a successful alter-
native to these conditions, employing tetraphenylphospho-
nium mono-peroxysulfate (TPPP) as the stoichiometric oxi-
dant; under these new conditions base is not required and
water is not needed as a solvent, so allowing reactions to
be performed at sub-zero temperatures.[7d] This system has
afforded enantiomeric excesses of up to 97% and has al-
lowed us to complete a highly enantioselective synthesis of
levcromakalim.[7e]
We reasoned that the attachment of asymmetric centres
in an exocyclic substituent on the iminium nitrogen atom,
[a] School of Chemistry, University of East Anglia, University
Plain,
Norwich, Norfolk NR4 7TJ, UK
Fax: +44-(0)1603-593008
E-mail: p.page@uea.ac.uk
[b] Department of Chemistry, Loughborough University, Lough-
borough,
Leicestershire LE11 3TU, UK
[c] NPIL Pharmaceuticals (UK) Ltd,
P.O. Box 521, Leeds Road, Huddersfield HD2 1GA, UK
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P. C. B. Page, B. R. Buckley, M. M. Farah, A. J. Blacker
FULL PAPER
Scheme 1.
We have postulated a catalytic cycle for an oxaziridinium erally involve a resolution at some point during the synthe-
ion as the oxidative intermediate (Scheme 1) and have sis, but to avoid this, the synthesis can be achieved from
1
shown that this intermediate can be detected by H NMR commercially available enantiomerically pure (R)- or (S)-
spectroscopy.[7f] We believe that the first stage involves the BINOL 11. Generation of 10 has been described by Maza-
formation of an initial adduct 7, uncharged at nitrogen, leyrat from a dimethylbinaphthalene,[11] which in turn can
formed by (probably reversible) nucleophilic attack of the be synthesized from BINOL.[9]
oxidant on the iminium salt. This is followed by irreversible
expulsion of sulfate to give the oxaziridinium ion, which we
suspect to be the rate-determining step under the reaction
conditions. Oxygen may then be transferred to a substrate
in a subsequent step. An interesting but complicating fea-
ture of these processes is that it is not one but two diastereo-
isomeric oxaziridinium salts that may be formed by attack
of oxidant at the si or re face of the iminium species. Each
may deliver the oxygen atom to either of the prochiral faces
of the alkene substrate with a different degree of enanti-
ocontrol, and the resulting oxaziridinium species may be in
competition for the alkene substrate.
As a result of our research into the development of more
selective iminium salt epoxidation catalysts we have re-
ported our preliminary studies on a new family of catalyst,
in which our original isoquinolinium/biphenyl moiety has
been replaced by a binaphthalene structure fused to a
seven-membered azepinium system, as in 6.[6,9] We report
Scheme 2. Retrosynthetic analysis of the desired iminium salts.
here in full the preparation and use of several related cata-
lysts, which contain a range of substituted 5-amino-2,2-di-
methyl-4-phenyl-1,3-dioxanes and isopinocampheylamine
moieties.
Using (R)-BINOL [(R)-11] in dichloromethane with tri-
fluoromethanesulfonic anhydride, 4-(dimethylamino)pyr-
idine, and 2,6-lutidine, the required product bis-triflate pro-
tected species 12 was produced in near-quantitative yield
after four hours (Scheme 3).[13] Subsequent cross-coupling
with methylmagnesium bromide and the nickel catalyst
We envisaged that the mode of access to these catalysts [NiCl2(dppp)2] afforded the (R)-dimethylated compound
would be by cyclocondensation of amines with the bromo- (R)-13, again in excellent yield (90%).[14]
Results and Discussion
aldehyde 8 as we have previously reported. This compound
Synthesis of the desired bis(bromomethyl)binaphthalene
could be synthesized from the oxepine 9 by ring opening (R)-14 has also been reported in the literature; the route
with bromine; synthesis of the oxepine 9 could in turn be involves the use of NBS in boiling carbon tetrachloride
accomplished by cyclization of the bis(hydroxymethyl) com- using benzoyl peroxide as the initiator, and afforded the
pound 10 (Scheme 2), a route used successfully by us for product in 64% yield after 24 h (Scheme 4).[9] In our hands,
the synthesis of the corresponding biphenyl derivatives, the however, this process was occasionally unreliable, and what
dibenzo[c,e]azepinium salts.[7c] Compound 10 is not com- we believe to be the tribromo compound (R)-15 was some-
mercially available, but several syntheses of 10, in enantio- times formed as the major product, as indicated by the pres-
merically pure form, have been reported.[10–12] These gen- ence of a singlet proton signal at δ = 6.22 ppm and a double
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Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
per,[11] we noted a brief comment that the bis(bromo-
methyl)binaphthalene (R)-14 can be directly converted into
the oxepine by heating in 1,4-dioxane/saturated sodium car-
bonate solution (Scheme 6). Indeed, cyclization under these
conditions did occur, and the (R)-oxepine (R)-9 was pro-
duced in 76% yield after 36 h. Ring opening of oxepine
(R)-9 using bromine in carbon tetrachloride under reflux
afforded the (R)-bromoaldehyde (R)-8 in 68% yield. Re-
peating the synthetic sequence with the (S)-enantiomer of
BINOL produced the corresponding (S)-bromoaldehyde
(S)-8 in comparable yields. HPLC analysis of the two enan-
tiomeric bromoaldehydes indicated that each retained
greater than 99% ee.
Scheme 3. Formation of the (R)-bis-methylene compound (R)-13.
Reagents and conditions: i: Tf2O, DMAP (cat.), 2,6-lutidine, DCM,
–30 °C to room temp., 99%; ii: MeMgBr, NiCl2(dppp)2, Et2O, 12 h,
90%.
1
doublet at δ = 4.24 ppm in the H NMR spectrum. This
side product, formed under these reaction conditions, has
also been noted by RajanBabu.[15]
Scheme 6. Formation of (R)-bromoaldehyde (R)-8. Reagents and
conditions: i: Na2CO3 (satd. aq.)/1,4-dioxane (1:1), reflux, 36 h,
76%; ii Br2, CCl4, reflux, 1 h, 68%.
Scheme 4. Bromination of (R)-13 with NBS. Reagents and condi-
tions: NBS (2 equiv.), solvent, heat or light.
With both enantiomers of the bromoaldehyde available,
several new iminium salts 17–23 were synthesized by cy-
clocondensation with a range of amines under our standard
conditions, by treatment of the bromoaldehydes with pri-
mary amines in ethanolic solution. Addition of sodium tet-
raphenylborate to the reaction mixture provides the imin-
ium tetraphenylborate salts, which are generally highly crys-
talline (Scheme 7, Table 1).
Slight modification of this procedure had a dramatic ef-
fect upon the yield of the reaction. Replacing the initiator
with AIBN, removing the heat, and stirring at room tem-
perature for 5 h under visible-light irradiation (150 W) af-
forded the desired compound (R)-14 in up to 88% yield.
Further modification by replacing the carcinogenic carbon
tetrachloride solvent with cyclohexane did not alter the rate
or yield of the reaction.
Conversion of the (R)-bis(bromomethyl)binaphthalene
species (R)-14 into the bis(hydroxymethyl)binaphthalene
(R)-10 required the formation of the intermediate diester
(R)-16 with potassium acetate and a catalytic amount of
tetrabutylammonium bromide in DMF (Scheme 5). Subse-
quent hydrolysis with aqueous potassium hydroxide (1 )
afforded the (R)-bis(hydroxymethyl)binaphthalene (R)-10
as colourless plates in 88% overall yield.
Scheme 7. Preparation of catalysts.
With the catalysts in hand, we were able to test their
effectiveness in the epoxidation of our test substrate 1-phen-
ylcyclohexene (Scheme 8, Table 2). Catalyst 6, pairing the
(S,S)-amine with the (Rax)-BINAP unit, showed the best
reaction profile, providing the highest enantiomeric excesses
(up to 91%), and was also the most reactive (complete con-
version after just 20 min). Catalyst 17, pairing the (S,S)-
amine with the (Sax)-BINAP unit, and thus a diastereoiso-
mer of 6, shows poorer enantiomeric excess and poorer re-
activity, presumably a result of a mismatch between the in-
trinsic enantiocontrol induced by the two components. The
Scheme 5. Formation of the (R)-bis(hydroxymethyl) compound
(R)-10. Reagents and conditions: i: KCO2CH3, Bu4NBr (cat.),
DMF, 80 °C, 20 h; ii: KOH (aq. 50%): 1,4-dioxane (1:1), ∆, 24 h,
88%.
Attempted cyclization of (R)-10 to form the desired oxe-
pine (R)-9 under the conditions developed for the corre-
sponding biphenyl derivative [HBr (aq. 24%), 100 °C, 1 h]
was, however, unsuccessful.[7c] Increasing the concentration
of the HBr or the reaction time had no effect, and complete
recovery of the starting material was observed in each case.
Fortunately, upon closer inspection of the Mazaleyrat pa- Scheme 8.
Eur. J. Org. Chem. 2009, 3413–3426
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P. C. B. Page, B. R. Buckley, M. M. Farah, A. J. Blacker
FULL PAPER
Table 1. Preparation of catalysts.[a]
sense of induced enantiocontrol appears to be driven princi-
pally by the stereochemistry of the BINAP unit. The isopin-
ocampheyl moiety offers poorer stereocontrol in the epox-
idation process, and thus catalysts 22 and 23 produce epox-
ides with more moderate enantiomeric excesses.
The catalysts were next used in the epoxidation of a
range of other alkenes under similar conditions (Table 3).
Catalyst 20, containing an electron-donating methoxy
group, provided enantioselectivities similar to or higher
than catalyst 6 for most substrates, an exception being when
1-phenylcyclohexene (20: 80% ee, cf. 6: 91% ee) and 1-
phenyl-3,4-dihydronaphthalene (20: 81% ee, cf. 6: 95% ee)
were used as substrates.
Table 3. Epoxidation of various alkenes using catalysts 6, 18–21.[a]
[a] Reaction conditions: a) amine (1 equiv.), (R)- or (S)-2Ј-(bro-
momethyl)-1,1Ј-binaphthalene-2-carboxaldehyde (1.10 equiv.), eth-
anol, 40 °C, 12 h; b) sodium tetraphenylborate (1.10 equiv.), aceto-
nitrile, 5 min. [b] Isolated yield.
Table 2. Epoxidation of 1-phenylcyclohexene with catalysts 6, ent-
6, 17–23.[a]
Catalyst
% Yield[b]
% ee[c]
Configuration[d]
6
69
66
54
66
69
71[e]
70
40
44
91
88
78
74
79
80
76
53
58
(–)-1S,2S
(+)-1R,2R
(+)-1R,2R
(–)-1S,2S
(–)-1S,2S
(+)-1R,2R
(–)-1S,2S
(–)-1S,2S
(+)-1R,2R
ent-6
17
18
19
20
21
22
23
[a] Epoxidation conditions: iminium salt (5 mol-%), Oxone
(2 equiv.), Na2CO3 (4 equiv.), MeCN/H2O (1:1), 0 °C, 2 h. [b] Con-
1
version evaluated from the H NMR spectra by integration of al-
[a] Epoxidation conditions: iminium salt (5 mol-%), Oxone
kene and epoxide peaks. [c] Isolated yield. [d] Enantiomeric excess
determined by 1H NMR spectroscopy with Eu(hfc)3 (10 mol-%) as
chiral shift reagent or by Chiral HPLC on a chiracel OD Column
or by Chiral GC. [e] The absolute configuration of the major en-
antiomer was determined by comparison of the optical rotation
with data reported in the literature. [f] Epoxidation conditions: im-
inium salt (5 mol-%), Oxone (2 equiv.), NaHCO3 (5 equiv.), MeCN/
H2O (10:1), 0 °C, 2 h. [g] 3 h reaction time. [h] 4 h reaction time. [i]
5 h reaction time.
(2 equiv.), Na2CO3 (4 equiv.), MeCN/H2O (1:1), 0 °C, 2 h. [b] Iso-
1
lated yield. [c] Enantiomeric excess determined by H NMR spec-
troscopy with (+)-Eu(hfc)3 (10 mol-%) as chiral shift reagent or by
Chiral GC. [d] The absolute configuration of the major enantiomer
was determined by comparison of the optical rotation with data
reported in the literature. [e] Epoxidation conditions: iminium salt
(5 mol-%), Oxone (2 equiv.), NaHCO3 (5 equiv.), MeCN/H2O
(10:1), 0 °C, 2 h.
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Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
Due to poorer reactivity portrayed by catalysts 18–21 un- just 0.5 mol-% of catalyst, but a loss in enantioselectivity is
der our standard epoxidation conditions (1:1 acetonitrile/ commonly observed. In this case, however, catalyst loadings
water, Na2CO3, Oxone), for example only 5–10% conver- can be so low that effective epoxidation of 1.0 g of 1-phenyl-
sion typically being observed after six hours for stilbene cyclohexene, with 68% yield and 88% ee, can be achieved
substrates, we also utilized the reaction conditions devel- using just 5 mg of catalyst (0.1 mol-%). This is an unpre-
oped by Yang[5] (10:1 acetonitrile/water, NaHCO3, Oxone), cedently low level of catalyst loading for an organocatalytic
which led typically to complete consumption of alkene in species.
around two hours. Because of the more acidic nature of the
reaction medium, however, hydrolysis of the epoxide prod-
ucts to the corresponding diols occurred in some cases, par-
Table 5. Catalyst loading study on the epoxidation of 1-phenylcy-
clohexene with catalyst 6.[a]
Catalyst [mol-
%]
Time [h]
% Yield[b] % ee[c]
Configura-
tion[d]
ticularly for 1-phenyl-3,4-dihydronaphthalene, where com-
plete conversion to the diol was observed in two hours.
When 1-phenylcyclohexene was used as substrate, between
11% and 20% conversion to diol was observed. Hydrolysis
to diol products was not observed under our standard con-
ditions.
Catalyst 6 exhibited the highest degree of enantiocontrol,
giving 95% ee for phenyl-1,2-dihydronaphthalene, one of
the highest ee values ever reported for iminium salt-medi-
ated epoxidation.
5.0
1.0
0.5
0.1
0.2
1.1
2.0
6.0
69
64
65
68
91
91
91
88
(–)-1S,2S
(–)-1S,2S
(–)-1S,2S
(–)-1S,2S
[a] Conditions: Oxone (2 equiv.), Na2CO3 (4 equiv.), MeCN/H2O
(1:1), 0 °C. [b] Isolated yields. [c] Enantiomeric excesses were deter-
mined by 1H NMR spectroscopy in the presence of (+)-Eu(hfc)3
(10 mol-%). [d] The absolute configurations of the major enantio-
mers were determined by comparison of the optical rotation with
data reported in the literature.
Several cycloalkenes of varying ring sizes were submitted
to the asymmetric epoxidation reaction (Table 4). Reactions
were carried out using just 1 mol-% of catalyst 6. Again,
good conversions to epoxides were achieved, and, interest-
ingly, the five- and seven-membered ring cycloalkenes were
less reactive than was 1-phenylcyclohexene. The reactions
took almost five times as long to approach completion, and
enantioselectivities were poorer than those observed for 1-
phenylcyclohexene: 1-phenylcyclopentene oxide was formed
in 55% ee and 1-phenylcycloheptene in 76% ee. This obser-
vation is difficult to explain, but presumably results from
conformational effects in the cycloalkenes and stereoelec-
tronic effects in the epoxidation transition states.
Conclusions
Catalyst 6 is one of the most active iminium salt catalysts
that we have discovered. It is also one of the most enantio-
selective iminium salt epoxidation catalysts ever reported,
and is effective at remarkably low catalyst loading. Gen-
erally, organic catalysts require higher catalyst loadings, and
a breakdown of the active species is sometimes observed.
In the case of catalyst 6, the enantioselectivity appears to
be almost independent of catalyst loading, and decreasing
the amount of catalyst merely increases the reaction time.
Table 4. Effect of ring size on the epoxidation of several cycloal-
kenes with catalyst 6.[a]
Experimental Section
(R)-1,1Ј-Binaphthalene-2,2Ј-diyl Bis(trifluoromethanesulfonate) (R)-
12: [16](R)-11 (3.00 g, 10.50 mmol) was dissolved in dichlorometh-
ane (60 mL), and the solution cooled to –30 °C and stirred at this
temperature for 5 min. 4-(Dimethylamino)pyridine (0.51 g,
4.20 mmol), 2,6-lutidine (3.70 mL, 31.40 mmol) and triflic anhy-
dride (5.30 mL, 31.40 mmol) were added. The resulting dark-brown
mixture was allowed reach ambient temperature and stirred over-
night. Silica gel was added to the solution and the solvent removed
in vacuo. The product mixture, adsorbed onto silica gel, was trans-
ferred to a sintered glass funnel, and the material washed with hex-
ane until the product had eluted. The solvent was removed in vacuo
to give a colourless solid, which was crystallized from hexane to
afford the product as colourless crystals (5.72 g, 99%); m.p. 76–
78 °C. [α]2D0 = –147.7 (c = 1.01, CHCl3), [ref.[16] +142.0 (c 1.04,
CHCl3), for (S)-enantiomer]. 1H NMR (400 MHz, CDCl3): δ =
7.17–7.19 (m, 2 H, 2 CH arom., binap-3,-3Ј), 7.32–7.36 (m, 2 H,
2 CH arom., binap-7,-7Ј), 7.49–7.56 (m, 4 H, 4 CH arom., binap-
8,-8Ј-9,9Ј), 7.94 (d, J = 8.2 Hz, 2 H, 2 CH arom., binap-4,-4Ј), 8.07
(d, J = 9.0 Hz, 2 H, 2 CH arom., binap-6,-6Ј) ppm. 13C NMR
(100 MHz, CDCl3): δ = 116.5 (q, J = 79.5 Hz, 2 CF3, 2 C quat.),
119.3 (2 CH arom., binap-8,-8Ј), 123.5 (2 C quat., arom., binap-1,-
1Ј), 126.8 (2 CH arom., binap-3,-3Ј), 127.3 (2 CH arom., binap-7,-
[a] Conditions: Iminium salt (1 mol-%), Oxone (2 equiv.), Na2CO3
(4 equiv.), MeCN/H2O (1:1), 0 °C. [b] Isolated yields. [c] Enantio-
meric excesses were determined by 1H NMR spectroscopy in the
presence of (+)-Eu(hfc)3 (10 mol-%). [d] The absolute configura-
tions of the major enantiomers were determined by comparison of
the optical rotation with data reported in the literature.
Using catalyst 6 we also conducted a catalyst loading
study using as test substrate 1-phenylcyclohexene, with cat-
alyst loadings ranging from 0.1 to 5 mol-% (Table 5). We
were delighted and extremely surprised to observe a high
level of asymmetric induction with very low catalyst load-
ings. We have previously reported that it is possible to use 7Ј), 128.0 (2 CH arom., binap-9,-9Ј), 128.4 (2 CH arom., binap-4,-
Eur. J. Org. Chem. 2009, 3413–3426
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FULL PAPER
4Ј), 132.0 (2 CH arom., binap-6,-6Ј), 132.3 (2 C quat., arom., binap-
7.94 (d, J = 8.6 Hz, 2 H, 2 CH arom., binap-6,-6Ј) ppm. 13C NMR
5,-5Ј), 133.1 (2 C quat., arom., binap-10,-10Ј), 145.4 (2 C quat., (100 MHz, CDCl3): δ = 31.6 (2 Ar-CH2), 126.87 (2 CH arom.,
arom., binap-2,-2Ј). MS (ES): m/z = 568.0316. C22H16F6NO6S2 [M binap-7,-7Ј), 126.88 (2 CH arom., binap-8,-8Ј), 127.1 (2 CH arom.,
+ NH4]+ calcd. 568.0323.
binap-4,-4Ј), 127.8 (2 CH arom., binap-9,-9Ј), 128.2 (2 CH arom.,
binap-6,-6Ј), 129.9 (2 CH arom., binap-3,-3Ј), 132.5 (2 C quat.,
arom., binap-5,-5Ј), 133.3 (2 C quat., arom., binap-10,-10Ј), 134.1
(2 C quat., arom., binap-2,-2Ј), 134.2 (2 C quat., arom., binap-1,
-1Ј). MS (EI): m/z = 437.9612. C22H16Br2 [M+] calcd. 437.9619
ppm.
(S)-1,1Ј-Binaphthalene-2,2Ј-diyl Bis(trifluoromethanesulfonate [(S)-
12]: Prepared in an identical manner to the (R)-enantiomer (R)-12
above, from (S)-1,1Ј-binaphthalene-2,2Ј-diol (S)-11 (3.00 g,
10.50 mmol). Colourless crystals (5.72 g, 99%), having almost iden-
tical spectroscopic data to (R)-12: m.p. 75–77 °C. [α]2D0 = +145.0 (c
= 1.00, CHCl3).
(S)-2,2Ј-Bis(bromomethyl)-1,1Ј-binaphthalene [(S)-14]:[17] Prepared
in an identical manner to the (R)-enantiomer (R)-14 above, from
(S)-13 (2.00 g, 7.08 mmol). Colourless crystals (6.32 g, 90%), hav-
ing almost identical spectroscopic data to (R)-14: m.p. 180–182 °C;
[ref.[17] m.p. 181–182 °C]. [α]2D0 = –158.0 (c = 1.00, benzene); [ref.[17]
[α]2D0 = –157.3 (c = 1.00, benzene)].
(R)-2,2Ј-Dimethyl-1,1Ј-binaphthalene [(R)-13]:[14] (R)-12 (13.70 g,
24.87 mmol) and [1,3-bis(diphenylphosphanyl)propane]nickel(II)
chloride (1.17 g, 1.79 mmol) were dissolved in anhydrous diethyl
ether (100 mL). The reaction was cooled to –30 °C, and methyl-
magnesium bromide (3  in Et2O, 33.16 mL, 99.48 mmol) added
dropwise over 30 min. The reaction was allowed to reach room
temperature and stirred for 16 h. The resulting dark green reaction
mixture was diluted with diethyl ether (100 mL) and filtered
through a pad of Celite. The filtrate was washed with 35% aqueous
hydrochloric acid (20 mL), water (100 mL) and brine (100 mL). Re-
moval of the solvent under reduced pressure gave a reddish crude
oil, which was purified by column chromatography, eluting with
ethyl acetate/hexane (1:4), to give a colourless powder. Crystalli-
zation from methanol afforded the product as colourless crystals
(6.32 g, 90%); m.p. 74–78 °C; [ref.[14] m.p. 67–71 °C]. [α]2D0 = –40.0
(R)-2,2Ј-Bis(hydroxymethyl)-1,1Ј-binaphthalene [(R)-10]:[11] A solu-
tion of (R)-14 (3.50 g, 8.0 mmol) was dissolved in dimethylform-
amide (300 mL) and stirred at 80 °C with potassium acetate (3.75 g,
38.2 mmol) and tetrabutylammonium bromide (1.0 g) for 24 h. The
mixture was cooled, diluted with brine (150 mL) and extracted with
diethyl ether (3ϫ100 mL). The organic solutions were combined
and washed with brine (2ϫ50 mL), dried (MgSO4), and the sol-
vents removed under reduced pressure to afford diacetate (R)-16
as a pale yellow/brown oil, recrystallized from chloroform/hexane.
Compound (R)-16 (3.0 g, 7.5 mmol) was then hydrolysed in a boil-
ing mixture of aqueous potassium hydroxide (50% in water) and
1,4-dioxane (1:1, 100 mL) for 24 h. The solution was cooled and
extracted with diethyl ether (3ϫ50 mL). The organic layers were
combined and washed with brine (2ϫ50 mL), and the solvents re-
moved to give a crude yellow/brown oil which was crystallized from
chloroform/hexane to give colourless crystals (2.10 g, 88%); m.p.
167–169 °C. [α]2D0 = +63.2 (c = 1.35, acetone) [ref.[11] [α]2D4 = –67.5
(c = 1.12, CHCl3) [ref.[14] [α]2D0 = –35.6 (c = 1.00, CHCl3)]. IR (film):
νmax = 3053, 2246, 1594, 1506, 1422, 1379, 1351 cm–1. H NMR
1
˜
(400 MHz, CDCl3): δ = 2.09 (s, 6 H, 2 Ar-CH3), 7.10 (dd, J = 8.5,
0.96 Hz, 2 H, 2 CH arom., binap-3,-3Ј), 7.23–7.28 (m, 2 H, 2 CH
arom., binap-7,-7Ј), 7.42–7.46 (m, 2 H, 2 CH arom., binap-8,-8Ј),
7.56 (d, J = 8.5 Hz, 2 H, 2 CH arom., binap-4,-4Ј), 7.92–7.95 (m, 4
H, 4 CH arom., binap-9,-9Ј and binap-6,-6Ј) ppm. 13C NMR
(100 MHz, CDCl3): δ = 20.1 (2 CH3, 2 Ar-CH3), 124.9 (2 CH
arom., binap-7,-7Ј), 125.7 (2 CH arom., binap-8,-8Ј), 126.1 (2 CH
arom., binap-4,-4Ј), 127.3 (2 CH arom., binap-9,-9Ј), 127.8 (2 CH
arom., binap-6,-6Ј), 128.8 (2 CH arom., binap-3,-3Ј), 132.2 (2 C
quat., arom., binap-5,-5Ј), 132.8 (2 C quat., arom., binap-10,-10Ј),
134.3 (2 C quat., arom., binap-2,-2Ј), 135.2 (2 C quat., arom., binap-
1,-1Ј); MS (EI): m/z = 282.1400. C22H18 [M+] calcd. 282.1409 ppm.
(c = 1.00, acetone) for (S)-enantiomer]. IR (film): νmax = 3384,
˜
3057, 1648, 1507, 1428, 1216, 1013, 822 cm–1. 1H NMR (250 MHz.
CDCl3): δ = 3.26 (br. s, 2 H), 4.08 (d, J = 11.1 Hz, 2 H), 4.37 (d,
J = 11.1 Hz, 2 H), 7.01 (d, J = 8.24 Hz, 2 H), 7.17–7.27 (m, 2 H),
1.92–2.02 (m, 2 H), 7.68 (d, J = 8.8 Hz, 2 H, 2), 7.89–8.00 (m, 4
H) ppm. 13C NMR (100 MHz. CDCl3): δ = 63.4, 126.3, 126.5,
126.7, 127.7, 128.5, 129.0, 133.5, 133.6, 134.7, 137.6. MS: m/z =
332.1650. C22H22NO2 (M+NH4) calcd. 332.1651 ppm.
(S)-2,2Ј-Dimethyl-1,1Ј-binaphthalene [(S)-13]: Prepared in an iden-
tical manner to the (R)-enantiomer (R)-13 above from (S)-12
(13.70 g, 24.87 mmol). Colourless crystals (6.32 g, 90%), having al-
(R)-2,7-Dihydrodinaphtho[2,1-c;1Ј,2Ј-e]oxepine [(R)-9]:[12] (R)-14
(1.16 g, 2.65 mmol) was suspended in a mixture of saturated aque-
ous sodium carbonate (40 mL) and 1,4-dioxane (40 mL). The mix-
ture was heated under reflux for 36 h, cooled to room temperature,
most identical spectroscopic data to (R)-13: m.p. 72–74 °C. [α]2D0
+38.0 (c = 1.00, CHCl3).
=
(R)-2,2Ј-Bis(bromomethyl)-1,1Ј-binaphthalene [(R)-14]:[17] (R)-13 and extracted with diethyl ether (2ϫ40 mL). The combined or-
(2.00 g, 7.08 mmol) was dissolved in cyclohexane (14 mL), and N-
ganic extracts were washed with brine (2ϫ30 mL) and dried
bromosuccinimide (2.77 g, 15.58 mmol) and azobis(isobutyronitr-
(Na2SO4), and the solvent removed in vacuo to give a yellow oil.
ile) (0.12 g, 0.71 mmol) were added with stirring. The mixture was The crude product was purified by flash column chromatography
heated under reflux for 3 h, after which time complete disappear-
ance of the starting material was observed by TLC. After cooling
using ethyl acetate/light petroleum (0:100–5:95) as eluent to afford
the product as a colourless solid (0.30 g, 81%); m.p. 184–186 °C;
to room temperature, ethyl acetate (5 mL) and water (30 mL) were [ref.[12] m.p. 188–189 °C]. [α]2D0 = –551.2 (c = 1.00, CHCl3). IR
added to dissolve excess NBS and to allow trituration. The re-
sulting suspension was stirred for 1 h, after which time precipi-
tation had ceased. The mixture was filtered to afford the product
as colourless solid (1.54 g, 50%); m.p. 180–183 °C [ref.[17] m.p. 171–
174 °C]. [α]2D0 = +186.4 (c = 1.00, benzene) [ref.[17] [α]2D0 = +148.0
(film): νmax = 3049, 2959, 2923, 1594, 1507, 1463, 1367, 1237,
˜
1
1195, 1057, 909, 828 cm–1. H NMR (400 MHz, CDCl3): δ = 4.12
(d, J = 11.3 Hz, 2 H, Ar-CH2O), 4.56 (d, J = 11.3 Hz, 2 H, Ar-
CH2O), 7.19–7.25 (m, 2 H, 2 CH arom., binap-3,-3Ј), 7.41–7.47 (m,
4 H, 4 CH arom., binap-7,-7Ј, binap-8,-8Ј), 7.55 (d, J = 8.4 Hz, 2
(c = 1.70, benzene)]. IR (film): νmax = 3049, 2360, 1506, 1432, H, 2 CH arom., binap-4,-4Ј), 7.89–7.94 (m, 4 H, 4 CH arom., binap-
˜
1
1211, 818, 759 cm–1. H NMR (400 MHz, CDCl3): δ = 4.17 (s, 4
6,-6Ј, binap-9,-9Ј) ppm. 13C NMR (100 MHz, CDCl3): δ = 67.5
H, 2 Ar-CH2), 7.00 (d, J = 8.6, Hz, 2 H 2 CH arom., binap-3,-3Ј), (2 CH2, 2 Ar-CH2), 125.95 (2 CH arom., binap-7,-7Ј), 125.98 (2 CH
7.17–7.19 (m, 2 H, 2 CH arom., binap-7,-7Ј), 7.39–7.41 (m, 2 H,
2 CH arom., binap-8,-8Ј), 7.67 (d, J = 8.6 Hz, 2 H, 2 CH arom.,
binap-4,-4Ј), 7.85 (d, J = 8.2 Hz, 2 H, 2 CH arom., binap-9,-9Ј),
arom., binap-8,-8Ј), 127.4 (2 CH arom., binap-4,-4Ј), 127.6 (2 CH
arom., binap-9,-9Ј), 128.4 (2 CH arom., binap-6,-6Ј), 129.2 (2 CH
arom., binap-3,-3Ј), 131.2 (2 C quat., arom., binap-5,-5Ј), 133.56
3418
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3413–3426

Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
(2 C quat., arom., binap-10,-10Ј), 133.64 (2 C quat., arom., binap-
2,-2Ј), 135.5 (2 C quat., arom., binap-1,-1Ј) ppm. MS (ESI): m/z =
314.1542. C22H20NO [M + NH4]+ calcd. 314.1545.
from dichloromethane to give colourless crystals (10.10 g, 99%);
m.p. 102–103 °C. [α]2D0 = +52.8 (c = 1.00, CHCl ). IR (film): νmax
˜
3
= 3364 (OH), 2977, 1689 (C=O), 1614, 1515, 1444, 1366, 1225,
1166, 1058 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.43 [s, 9 H,
NCO2C(CH3)3], 2.98–3.04 (m, 2 H, Ar-CH2, H3), 3.70 (s, 3 H,
CO2CH3), 4.54 (q, J = 8.2 Hz, 1 H, CHN, H2), 5.13 (d, J = 8.4 Hz,
1 H, NH), 6.75 (d, J = 8.3 Hz, 2 H, 2 CH arom., H7, H8), 6.96 (d,
J = 8.3 Hz, 2 H, 2 CH arom., H5, H6) ppm. 13C NMR (100 MHz,
CDCl3): δ = 28.3 [3 CH3, NCO2C(CH3)3], 37.5 (CH2, ArCH2, C3),
52.4 (CH3, CO2CH3), 54.4 (CH, CHN, C2), 80.4 [C quat.,
NCO2C(CH3)3], 115.6 (2 CH arom., C7, C8), 127.1 (C quat.,
arom., ipso to C3 in Ar gp., C4), 130.3 (2 CH arom., C5, C6),
155.47 (C quat., N-Boc C=O), 155.53 (C quat., arom., ipso to OH
in Ar gp., C9), 172.8 (C quat., C=O, CO2CH3) ppm. MS (FAB):
m/z = 296.1496. C15H22NO5 [M + H]+ calcd. 296.1498.
(S)-2,7-Dihydrodinaphtho[2,1-c;1Ј,2Ј-e]oxepine [(S)-9]: Prepared in
an identical manner to the (R)-enantiomer (R)-9 above, from (S)-
14 (1.16 g, 2.65 mmol). Colourless crystals (0.30 g, 81%), having
almost identical spectroscopic data to (R)-9: m.p. 184–186 °C. [α]
20
= +568.2 (c = 1.00, CHCl3).
D
(R)-2Ј-Bromomethyl-1,1Ј-binaphthalene-2-carboxaldehyde [(R)-8]:[6]
(R)-9 (0.50 g, 1.69 mmol) was dissolved in cyclohexane, and the
solution cooled to 0 °C. Bromine (0.31 g, 1.86 mmol) was added
dropwise with stirring over 10 min. After stirring for a further
5 min at this temperature, the reddish coloured reaction mixture
was heated under reflux for 1 h, becoming a pale yellow colour.
The solvent was removed in vacuo, and the resulting yellow residue
dissolved in diethyl ether (30 mL), and washed with saturated aque-
ous sodium carbonate (2ϫ30 mL) and brine (2ϫ30 mL). The
combined organic extracts were dried (Na2SO4), and the solvent
removed in vacuo to give a yellow oil. The crude product was puri-
fied by flash column chromatography using ethyl acetate/light pe-
troleum (0:100) as eluent, to afford the product as a colourless solid
(2S)-Methyl 2-(tert-Butyloxycarbonylamino)-3-(4-methoxyphenyl)-
propanoate:[18] (2S)-Methyl 2-(tert-butyloxycarbonylamino)-3-(4-
hydroxyphenyl)propanoate (9.90 g, 33.72 mmol) was dissolved in
dimethylformamide (70 mL), and ground potassium hydroxide
(2.31 g, 40.46 mmol) added. Iodomethane (2.52 mL, 40.46 mmol)
was added dropwise at 0 °C. The reaction mixture was stirred at
room temperature for 16 h, diluted with ethyl acetate (100 mL), and
washed with water (6ϫ50 mL) and brine (6ϫ50 mL). The organic
solution was dried (Na2SO4), and the solvent removed under re-
duced pressure to yield a colourless oil (9.38 g, 90%). IR (film):
(0.43 g, 68%); m.p. 150–152 °C; [ref.[6] m.p. 151–153 °C]. [α]2D0
=
+144.0 (c = 1.00, CHCl3); [ref.[6] [α]2D0 = +144.7 (c = 1.02, CHCl3)].
IR (film): νmax = 3057, 2845, 2357, 1688, 1616, 1593, 1509, 1429,
˜
1324, 1240, 1223, 1027, 909, 870, 821, 750, 730 cm–1. 1H NMR
(400 MHz, CDCl3): δ = 4.01 (d, J = 10.1 Hz, 1 H, Ar-CHHBr),
4.26 (d, J = 10.1 Hz, 1 H, Ar-CHHBr), 6.95 (dd, J = 8.5, 0.8 Hz,
1 H, CH arom., binap-7Ј), 7.16–7.29 (m, 3 H, 3 CH arom., binap-
3,-8Ј-4Ј), 7.40–7.46 (m, 1 H, CH arom., binap-7), 7.52–7.58 (m, 1
H, CH arom., binap-8), 7.65 (d, J = 8.6 Hz, 1 H, CH arom., binap-
4), 7.87 (d, J = 8.4 Hz, 1 H, CH arom., binap-6), 7.93 (d, J =
8.4 Hz, 1 H, CH arom., binap-6Ј), 7.98 (d, J = 8.5 Hz, 1 H, CH
arom., binap-9), 8.02 (d, J = 8.5 Hz, 1 H, CH arom., binap-9Ј), 8.14
(d, J = 8.6 Hz, 1 H, CH arom., binap-3Ј), 9.49 (d, J = 0.9 Hz, 1 H,
CHO) ppm. 13C NMR (100 MHz, CDCl3): δ = 31.9 (CH2, Ar-
CH2), 122.4 (CH arom., binap-3), 126.6 (CH arom., binap-7Ј), 126.9
(CH arom., binap-8Ј), 127.0 (CH arom., binap-4Ј), 127.39 (CH
arom., binap-8), 127.40 (2 CH arom., binap-6Ј,9Ј), 128.2 (CH
arom., binap-4), 128.5 (CH arom., binap-6), 129.2 (CH arom.,
binap-3Ј), 129.3 (CH arom., binap-7), 129.9 (CH arom., binap-9),
132.41 (C quat., arom., binap-5Ј), 132.42 (C quat., arom., binap-
10Ј), 132.5 (C quat., arom., binap-2), 133.0 (C quat., arom., binap-
5), 133.6 (C quat., arom., binap-2Ј), 134.6 (C quat., arom., binap-
1Ј), 136.3 (C quat., arom., binap-10), 141.6 (C quat., arom., binap-
1), 191.8 (CHO) ppm. MS (ESI): m/z = 392.0643. C22H19BrNO [M
+ NH4]+ calcd. 392.0650.
νmax = 3367, 2976, 1746 (C=O), 1715 (NC=O), 1612, 1514, 1441,
˜
1366, 1249, 1167, 1034 cm–1. 1H NMR (400 MHz, CDCl3): δ =
1.34 [s, 9 H, NCO2C(CH3)3], 2.92–2.97 (m, 2 H, Ar-CH2, H3), 3.63
(s, 3 H, CO2CH3), 3.70 (s, 3 H, ArOCH3), 4.46 (q, J = 8.2 Hz, 1
H, CHN, H2), 4.95 (d, J = 8.2 Hz, 1 H, NH), 6.75 (d, J = 8.7 Hz,
2 H, 2 CH arom., H7, H8), 6.96 (d, J = 8.7 Hz, 2 H, 2 CH arom.,
H5, H6) ppm. 13C NMR (100 MHz, CDCl3): δ = 28.3 [3 CH3,
NCO2C(CH3)3], 37.4 (CH2, ArCH2, C3), 52.2 (CH3, CO2CH3),
54.6 (CH, CHN, C2), 55.2 (CH3, ArOCH3), 79.8 [C quat.,
NCO2C(CH3)3], 113.9 (2 CH arom., C7, C8), 127.9 (C quat.,
arom., ipso to C3 in Ar gp., C4), 130.3 (2 CH arom., C5, C6), 155.1
(C quat., N-Boc C=O), 158.6 (C quat., arom., ipso to OCH3 in Ar
gp., C9), 172.5 (C quat., C=O, CO2CH3) ppm. MS (FAB): m/z =
310.1651. C16H24NO5 [M + H]+ calcd. 310.1655.
(4S,5R)-Methyl 5-(4-Methoxyphenyl)-2-oxo-1,3-oxazolidine-4-car-
boxylate:[18] (2S)-Methyl 2-(tert-butyloxycarbonylamino)-3-(4-
methoxyphenyl)propanoate (5.00 g, 16.26 mmol) was dissolved in
acetonitrile (200 mL). Solutions of potassium persulfate (8.79 g,
32.51 mmol) in water (150 mL) and copper(II) sulfate (0.80 g,
3.21 mmol) in water (50 mL) were added. The reaction mixture was
heated to 70 °C for 3 h under nitrogen, then cooled to room tem-
perature before being extracted with ethyl acetate (3ϫ70 mL). The
combined organic extracts were dried (Na2SO4), and the solvent
removed under reduced pressure to give a yellow oil. Column
chromatography with ethyl acetate/light petroleum (1:1) afforded a
colourless solid (1.03 g, 25%); m.p. 92–94 °C; [ref.[18] 94–96 °C].
[α]2D0 = +85.2 (c = 1.00, CHCl3); [ref.[18] [α]2D0 = +83.5 (c = 1.15,
(S)-2Ј-(Bromomethyl)-1,1Ј-binaphthalene-2-carboxaldehyde [(S)-8]:
Prepared in an identical manner to the (R)-enantiomer (R)-8 above,
from (S)-9 (0.50 g, 1.69 mmol). Colourless crystals (0.22 g, 34%),
having almost identical spectroscopic data to (R)-8: m.p. 153–
154 °C. [α]2D0 = –143.0 (c = 1.00, CHCl3).
(2S)-Methyl 2-(tert-Butyloxycarbonylamino)-3-(4-hydroxyphenyl)-
propanoate:[18] Triethylamine (9.63 mL, 69.06 mmol) was added to
a cooled solution of -tyrosine methyl ester hydrochloride salt
(8.00 g, 34.53 mmol) in dichloromethane (100 mL) at 0 °C. The
mixture was stirred for 30 min at 0 °C before a solution of tert-
butyloxycarbonyl anhydride (8.29 g, 37.98 mmol) in dichlorometh-
CHCl )]. IR (film): νmax = 3314, 2954, 2841, 1762 (C=O), 1612,
˜
3
1514, 1441, 1381, 1246, 1119, 1024, 921, 833, 735 cm–1. H NMR
1
(400 MHz, CDCl3): δ = 3.74 (s, 3 H, CO2CH3), 3.76 (s, 3 H,
ArOCH3), 4.24 (dd, J = 5.2, 0.6 Hz, 1 H, CHN, H4), 5.50 (d, J =
5.2 Hz, 1 H, ArCH, H5), 6.75 (s, 1 H, NH), 6.85 (d, J = 8.6 Hz, 2
H, 2 CH arom., H9, H10), 7.27 (d, J = 8.6 Hz, 2 H, 2 CH arom.,
ane (10 mL) was added dropwise. The mixture was stirred at room H7, H8) ppm. 13C NMR (100 MHz, CDCl3): δ = 53.2 (CH3,
temperature for 16 h, transferred to a separating funnel and washed
with 1  citric acid (2ϫ30 mL) and brine (2ϫ30 mL). The organic
solution was dried (Na2SO4), and the solvent removed under re-
duced pressure to give a colourless oil. Crystallization was achieved
CO2CH3), 55.4 (CH3, ArOCH3), 61.5 (CH, CHN, C4), 79.5 (CH,
ArCH, C5), 114.4 (2 CH arom., C9, C10), 127.1 (2 CH arom., C7,
C8), 129.9 (C quat., arom., ipso to C5 in Ar gp., C6), 158.6 (C
quat., NC=O, C2), 160.3 (C quat., arom., ipso to OCH3 in Ar gp.,
Eur. J. Org. Chem. 2009, 3413–3426
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3419

P. C. B. Page, B. R. Buckley, M. M. Farah, A. J. Blacker
FULL PAPER
C11), 170.3 (C quat., C=O, CO2CH3). MS (EI): m/z = 251.0799.
(2ϫ20 mL) and brine (2ϫ20 mL), dried (Na2SO4), and the solvent
C12H13NO5 [M+] calcd. 251.0794 ppm.
removed under reduced pressure to afford a colourless oil (4.75 g,
100%). [α]2D0 = –9.7 (c = 1.16, CHCl ). IR (film): νmax = 3380
˜
3
(4R,5R)-4-(Hydroxymethyl)-5-(4-methoxyphenyl)-1,3-oxazolidin-2-
one:[18] (4S,5R)-Methyl 5-(4-methoxyphenyl)-2-oxo-1,3-oxazolid-
ine-4-carboxylate (1.14 g, 4.55 mmol) was dissolved in ethanol
(30 mL), and the solution cooled to 0 °C (external) using an ice
bath. A solution of sodium borohydride (0.38 g, 10.01 mmol) in
ethanol (5 mL) was added dropwise to the mixture. After the ad-
dition was complete the ice bath was removed and the reaction
mixture stirred at room temperature for 55 min. The reaction mix-
ture was cooled to 0 °C and concentrated hydrochloric acid (2 mL)
added, followed by water (20 mL). The ethanol was removed under
reduced pressure and the remaining aqueous mixture extracted
with ethyl acetate (3ϫ40 mL). The combined organic extracts were
washed with brine (2ϫ30 mL), dried (Na2SO4), and the solvents
removed under reduced pressure to yield a colourless solid (0.95 g,
94%); m.p. 138–140 °C; [ref.[18] m.p. 140–142 °C]. [α]2D0 = +74.6 (c
= 1.01, acetone); [ref.[18] [α]2D0 = +74.8 (c = 1.08, acetone)]. IR (nu-
(OH), 2970, 1691 (NC=O), 1613, 1511, 1367, 1248, 1168, 1041, 912
cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.33 [s, 9 H, NCO2C(CH3)
3], 2.69 (d, J = 6.9 Hz, 2 H, Ar-CH2, H3), 3.44 (dd, J = 10.9,
5.0 Hz, 1 H, NCH-CHH-OH, H1), 3.54 (dd, J = 10.9, 4.0 Hz, 1
H, NCH-CHH-OH, H1Ј), 3.69 (s, 3 H, ArOCH3), 3.74 (d, J =
4.0 Hz, 1 H, CHN, H2), 4.88 (d, J = 6.2 Hz, 1 H, NH), 6.75 (d, J
= 8.6 Hz, 2 H, 2 CH arom., H7, H8), 7.05 (d, J = 8.6 Hz, 2 H,
2 CH arom., H5, H6) ppm. 13C NMR (100 MHz, CDCl3): δ = 28.4
[3 CH3, NCO2C(CH3)3], 36.5 (CH2, ArCH2, C3), 53.8 (CH, CHN,
C2), 55.2 (CH3, ArOCH3), 63.9 (CH2, CH2OH, C1), 79.6 [C quat.,
NCO2C(CH3)3], 113.9 (2 CH arom., C7, C8), 129.9 (C quat.,
arom., ipso to C3 in Ar gp., C4), 130.3 (2 CH arom., C5, C6), 156.3
(C quat., N-Boc C=O), 158.2 (C quat., arom., ipso to OCH3 in Ar
gp., C9) ppm. MS (FAB): m/z = 282.1710. C15H24NO4 [M + H]+
calcd. 282.1705.
(2S)-1-Acetoxy-2-tert-butyloxycarbonylamino-3-(4-methoxyphenyl)-
jol): νmax = 3239, 1725, 1614, 1514, 1459, 1376, 1251, 1174, 1062,
˜
propane:[18]
(2S)-2-(tert-butyloxycarbonylamino)-3-(4-methoxy-
1
1016, 828 cm–1. H NMR (400 MHz, [D6]acetone): δ = 3.76–3.80
phenyl)propan-1-ol (4.80 g, 17.06 mmol) was dissolved in dichloro-
methane (50 mL), and the solution cooled to 0 °C. Acetic anhy-
dride (1.94 mL, 20.60 mmol), N,N-diisopropylamine (3.60 mL,
20.60 mmol) and 4-(dimethylamino)pyridine (0.21 g, 1.72 mmol)
were added. The reaction mixture was stirred at room temperature
for 16 h. 1% aqueous HCl (40 mL) was added. The organic phase
was separated and washed with 1% HCl (2ϫ40 mL) and brine
(2ϫ40 mL). The organic solution was dried (Na2SO4) and the sol-
vent removed under reduced pressure to yield a red oil (5.20 g,
(m, 3 H, CHN, H4 and CH2OH, H6), 3.86 (s, 3 H, ArOCH3), 5.35
(d, J = 5.3 Hz, 1 H, ArCH, H5), 7.01 (d, J = 8.6 Hz, 2 H, 2 CH
arom., H10, H11), 7.41 (d, J = 8.6 Hz, 2 H, 2 CH arom., H8, H9)
ppm. 13C NMR (100 MHz, [D6]acetone): δ = 56.0 (CH, CHN, C4),
63.1 (CH3, ArOCH3), 64.2 (CH2, C6), 80.4 (CH, ArCH, C5), 115.4
(2 CH arom., C10, C11), 128.7 (2 CH arom., C8, C9), 133.2 (C
quat., arom., ipso to C5 in Ar gp., C7), 159.6 (C quat., NC=O,
C2), 161.3 (C quat., arom., ipso to OCH3 in Ar gp., C12) ppm. MS
(EI): m/z = 223.0843. C11H13NO4 [M+] calcd. 223.0845.
94%). [α]2D0 = –8.8 (c = 1.00, CHCl ). IR (film): νmax = 3360 (NH),
˜
3
(1R,2R)-(–)-2-Amino-1-(4-methoxyphenyl)propane-1,3-diol:[18]
A
2973, 1706 (C=O), 1612, 1511, 1456, 1368, 1242, 1169, 1040, 916,
821, 735 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.34 [s, 9 H,
NCO2C(CH3)3], 2.00 (s, 3 H, CH2-O-COCH3), 2.63–2.74 (m, 2 H,
Ar-CH2, H3), 3.69 (s, 3 H, ArOCH3), 3.92–3.96 (m, 3 H, CHN,
H2 and NCHCH2-O, H1), 4.58 (d, J = 6.8 Hz, 1 H, NH), 6.75 (d,
J = 8.6 Hz, 2 H, 2 CH arom., H7, H8), 7.02 (d, J = 8.6 Hz, 2 H,
2 CH arom., H5, H6) ppm. 13C NMR (100 MHz, CDCl3): δ =
20.9 (CH3, O-CO-CH3), 28.3 [3 CH3, NCO2C(CH3)3], 37.0 (CH2,
ArCH2, C3), 50.7 (CH, CHN, C2), 55.2 (CH3, ArOCH3), 65.0
(CH2, NCH-CH2-O, C1), 79.5 [C quat., NCO2C(CH3)3], 114.0
(2 CH arom., C7, C8), 129.2 (C quat., arom., ipso to C3 in Ar gp.,
C4), 130.2 (2 CH arom., C5, C6), 155.3 (C quat., N-Boc C=O),
158.3 (C quat., arom., ipso to OCH3 in Ar gp., C9), 170.9 (C quat.,
C=O); MS (EI): m/z = 323.1738. C17H25NO5 [M+] calcd. 323.1733
ppm.
mixture of (4R,5R)-4-(hydroxymethyl)-5-(4-methoxyphenyl)-1,3-
oxazolidin-2-one (0.66 g, 2.95 mmol) and 1  aqueous sodium hy-
droxide (30 mL) were heated under reflux for 45 min. The reaction
mixture was cooled to room temperature and extracted with ethyl
acetate (9 ϫ40 mL). The combined organic extracts were dried
(MgSO4) and the solvents removed under reduced pressure to af-
ford a colourless solid, which was recrystallized from methanol/
diethyl ether (0.51 g, 88 %); m.p. 129–131 °C; [ref.[18] m.p. 132–
134 °C]. [α]2D0 = –33.6 (c = 1.00, 2  aq. HCl); [ref.[6] [α]2D0 = –28.3
(c = 1.06, 2  aq. HCl)]. IR (nujol): νmax = 3339, 1619, 1584, 1517,
˜
1
1459, 1377, 1253, 1064, 873 cm–1. H NMR (400 MHz, CD3OD):
δ = 2.89–2.93 (m, 1 H, CHN, H2), 3.30 (dd, J = 10.8, 4.2 Hz, 1 H,
NCHCHH-O, H3), 3.43 (dd, J = 10.8, 4.2 Hz, 1 H, NCHCHH-O,
H3Ј), 3.80 (s, 3 H, ArOCH3), 4.50 (d, J = 7.2 Hz, 1 H, ArCH, H1),
6.93 (d, J = 8.7 Hz, 2 H, 2 CH arom., H7, H8), 7.29 (d, J = 8.7 Hz,
2 H, 2 CH arom., H5, H6) ppm. 13C NMR (100 MHz, [D6]ace-
tone): δ = 55.7 (CH3, ArOCH3), 59.9 (CH, CHN, C2), 64.0 (CH2,
C3), 75.4 (CH, ArCH, C1), 114.8 (2 CH arom., C7, C8), 128.8
(2 CH arom., C5, C6), 135.9 (C quat., arom., ipso to C1 in Ar gp.,
C4), 160.7 (C quat., arom., ipso to OCH3 in Ar gp., C9) ppm. MS
(FAB): m/z = 198.1127. C10H16NO3 [M + H] calcd. 198.1130.
(4R,5R)-4-(Acetoxymethyl)-5-(4-methoxyphenyl)-1,3-oxazolidin-2-
one:[18] (2S)-1-Acetoxy-2-(tert-butyloxycarbonylamino)-3-(4-meth-
oxyphenyl)propane (3.53 g, 10.92 mmol) was dissolved in acetoni-
trile (80 mL). Solutions of potassium persulfate (5.89 g,
21.83 mmol) in water (70 mL) and copper(II) sulfate (0.35 g,
2.16 mmol) in water (10 mL) were added. The reaction mixture was
heated to 70 °C for 2.5 h under nitrogen, cooled to room tempera-
ture, and extracted with ethyl acetate (3ϫ70 mL). The combined
(2S)-2-(tert-Butyloxycarbonylamino)-3-(4-methoxyphenyl)propan-1-
ol:[18] (2S)-Methyl 2-(tert-butyloxycarbonylamino)-3-(4-meth- organic extracts were dried (Na2SO4), and the solvent removed un-
oxyphenyl)propanoate (5.20 g, 16.91 mmol) was dissolved in dry
diethyl ether (100 mL) under a nitrogen atmosphere, and the re-
sulting solution cooled to 0 °C (external) using an ice bath. Lithium
borohydride (1.47 g, 67.62) was added to the cooled reaction mix-
ture in portions over 15 min. Methanol (40 mL) was added drop-
wise, and the reaction mixture stirred at room temperature over-
night. The reaction mixture was diluted with ethyl acetate
(100 mL), and saturated aqueous ammonium chloride added drop-
wise. The organic phase was separated and washed with water
der reduced pressure to yield a crude yellow oil. Column
chromatography with ethyl acetate/petroleum ether (1:1) afforded
a colourless solid (1.09 g, 38%); m.p. 99–100 °C. [α]2D0 = +55.8 (c =
1.29, CHCl ). IR (film): νmax = 3328 (NH), 2958, 2839, 1745
˜
3
(C=O), 1612, 1515, 1376, 1248, 1179, 1037, 917, 833, 732 cm–1. 1H
NMR (400 MHz, CDCl3): δ = 2.00 (s, 3 H, O-CO-CH3, H9), 3.72
(s, 3 H, ArOCH3), 3.89–3.94 (m, 1 H, CHN, H4), 4.07 (dd, J =
11.5, 5.8 Hz, 1 H, NCH-CHH-O, H6), 4.19 (dd, J = 11.5, 4.6 Hz,
1 H, NCH-CHH-O, H6Ј), 5.13 (d, J = 6.2 Hz, 1 H, ArCH, H5),
3420
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3413–3426

Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
6.83 (d, J = 8.7 Hz, 2 H, 2 CH arom., H13, H14), 6.95 (s, 1 H,
arom., C14). MS (FAB): m/z = 238.1448. C13H20NO3 [M + H]+
NH), 7.21 (d, J = 8.7 Hz, 2 H, 2 CH arom., H11, H12) ppm. 13C calcd. 238.1443.
NMR (100 MHz, CDCl3): δ = 19.7 (CH3, O-CO-CH3, C9), 54.3
General Procedure for the Formation of Formyl-Protected 5-Amino-
(CH3, ArOCH3), 58.1 (CH, CHN, C4), 63.4 (CH2, NCH-CH2-O,
C6), 79.0 (CH, ArCH, C5), 113.3 (2 CH arom., C13, C14), 126.5
(2 CH arom., C11, C12), 128.7 (C quat., arom., C10), 158.2 (C
quat., NC=O, C2), 159.2 (C quat., arom., ipso to OCH3 in Ar gp.,
C14), 169.8 (C quat., C=O, C8) ppm. MS (FAB): m/z = 266.1033.
C13H16NO5 [M + H]+ calcd. 266.1029.
1,3-dioxanes from Amino Diols: The amino diol was dissolved in
methanol (10 mL/g of aminodiol), and methyl formate (1.1 equiv.)
and sodium methoxide (0.1 equiv.) were added. The mixture was
stirred for 3.5 h and the solvent removed under reduced pressure.
The crude yellow oil was dissolved with in acetone (50 mL/g of
aminodiol), and 2,2-dimethoxypropane (10.0 equiv.) and cam-
phorsulfonic acid (0.1 equiv.) were added. The mixture was stirred
for up to 4 h and monitored by TLC. The solvents were removed
under reduced pressure, and the residue was re-dissolved in ethyl
acetate. The solution was washed with saturated aqueous sodium
hydrogen carbonate (2ϫ20 mL/g of aminodiol) and brine
(2ϫ20 mL/g of aminodiol), dried (MgSO4), and the solvents were
removed under reduced pressure.
(4R,5R)-5-(Formylamino)-4-(4-methoxyphenyl)-2,2-dimethyl-1,3-di-
oxane:[7] (1R,2R)-(–)-2-Amino-1-(4-methoxyphenyl)propane-1,3-
diol (0.63 g, 3.20 mmol) was dissolved in methanol (20 mL), and
methyl formate (0.22 mL, 3.52 mmol) added followed by a solution
of sodium methoxide (0.02 mL). The reaction mixture was stirred
overnight and the solvent removed under reduced pressure. The
crude product was dissolved in acetone (30 mL), and 2,2-dimeth-
oxypropane (5 mL, 31 mmol) and scandium triflate (0.16 g,
0.31 mmol) added. The mixture was stirred overnight and the sol-
vents removed under reduced pressure. The residue was dissolved
in ethyl acetate and the solution washed with saturated aqueous
(4S,5S)-5-(Formylamino)-2,2-dimethyl-4-phenyl-1,3-dioxane:[19] Pre-
pared according to the general procedure from (1S,2S)-(+)-2-
amino-1-phenylpropane-1,3-diol (5.00 g, 29.90 mmol). The product
was isolated as a colourless oil (6.61 g, 94%). IR (film): νmax =
˜
sodium hydrogen carbonate (2ϫ30 mL) and brine (2ϫ30 mL), 3295, 2990, 1668, 1505, 1381, 1200, 1089, 844, 700 cm–1. 1H NMR
and dried (Na2SO4). The solvents were removed under reduced
pressure to yield a crude yellow oil. Column chromatography with
ethyl acetate/light petroleum (1:2) afforded the product as a colour-
(400 MHz, CDCl3): δ = 1.49 (s, 3 H, CH3, H7 or H8), 1.53 (s, 3
H, CH3, H7 or H8), 3.80 (dd, J = 10.4, 1.6 Hz, 1 H, NCHCHH-
O, H6), 4.19 (dd, J = 10.4, 1.6 Hz, 1 H, NCHCHH-O, H6Ј), 4.23
(s, 1 H, NCH, H5), 5.14 (s, 1 H, ArCH, H4), 7.16–7.28 (m, 5 H,
less oil (0.75 g, 91%). [α]2D0 = –7.3 (c = 1.15, CHCl3); [ref.[6] [α]2D0
=
–2.7 (c = 1.20, CHCl )]. IR (film): νmax = 3302 (NH), 2988, 2871, 5 CH arom., Ph gp.), 7.89 (s, 1 H, NCHO) ppm. 13C NMR
˜
3
2243, 1673, 1512, 1378, 1247, 1196, 1083, 1036, 953, 836, 733, 628
(100 MHz, CDCl3): δ = 17.5 (CH3, C7 or C8), 28.7 (CH3, C7 or
1
cm–1. H NMR (400 MHz, CDCl3): δ = 1.54 (s, 3 H, CH3, H7or C8), 44.4 (CH, NCH, C5), 63.6 (CH2, C6), 70.6 (Ar-CH, C4), 98.9
H8), 1.58 (s, 3 H, CH3, H7 or H8), 3.78 (s, 3 H, ArOCH3), 3.87 (C quat., C2), 124.2 (2 CH arom., C10, C11), 126.7 (CH arom.,
(dd, J = 10.3, 1.8 Hz, 1 H, NCHCHH-O, H6), 4.23–4.27 (m, 2 H,
C14), 127.3 (2 CH arom., C12, C13), 137.0 (C quat., arom., C9),
NCH, H5 and NCHCHH-O, H6Ј), 5.16 (s, 1 H, Ar-CH, H4), 6.39 159.5 (NCHO, C15) ppm.
(d, J = 9.1 Hz, 1 H, NH), 6.87 (d, J = 8.7 Hz, 2 H, 2 CH arom.,
(4S,5S)-5-(Formylamino)-2,2-dimethyl-4-(4-nitrophenyl)-1,3-diox-
H12, H13), 7.23 (d, J = 8.7 Hz, 2 H, 2 CH arom., H10, H11), 7.97
(s, 1 H, NCHO) ppm. 13C NMR (100 MHz, CDCl3): δ = 18.6
(CH3, C7 or C8), 29.7 (CH3, C7 or C8), 45.5 (CH, NCH, C5), 55.2
(CH3, ArOCH3), 64.6 (CH2, C6), 71.4 (Ar-CH, C4), 99.7 (C quat.,
C2), 113.7 (2 CH arom., C12, C13), 126.5 (2 CH arom., C10, C11),
130.2 (C quat., arom., C9), 159.0 (C quat., arom., C14), 160.7
(NCHO, C15); MS (EI): m/z = 265.1318. C14H19NO4 [M+] calcd.
265.1314 ppm.
ane:[7] Prepared according to the general procedure from (1S,2S)-
(+)-2-amino-1-(4-nitrophenyl)propane-1,3-diol (3.00 g, 14.14
mmol). The product was isolated as a colourless oil (3.72 g, 94%).
[α]2D0 = +7.0 (c = 1.43, CHCl3); [ref.[6] [α]2D0 = +3.5 (c = 1.02,
CHCl )]. IR (film): νmax = 2992, 1684, 1601, 1521, 1382, 1346,
˜
3
1270, 1199, 1086, 856, 735 cm–1. 1H NMR (400 MHz, CDCl3): δ
= 1.48 (s, 3 H, CH3, H7 or H8), 1.54 (s, 3 H, CH3, H7 or H8),
3.77 (dd, J = 12.2, 1.8 Hz, 1 H, NCHCHH-O, H6), 4.26 (dd, J =
12.2, 1.8 Hz, 1 H, NCHCHH-O, H6Ј), 4.35 (dd, J = 9.8, 1.8 Hz, 1
H, NCH, H5), 5.22 (d, J = 1.8 Hz, 1 H, ArCH, H4), 6.36 (d, J =
9.8 Hz, 1 H, NH), 7.44 (d, J = 8.9 Hz, 2 H, 2 CH arom., H12,
H13), 7.86 (s, 1 H, NCHO), 8.12 (d, J = 8.9 Hz, 2 H, 2 CH arom.,
H10, H11) ppm. 13C NMR (100 MHz, CDCl3): δ = 18.5 (CH3, C7
or C8), 29.6 (CH3, C7 or C8), 45.1 (CH, NCH, C5), 66.3 (CH2,
C6), 71.6 (Ar-CH, C4), 100.1 (C quat., C2), 123.7 (2 CH arom.,
C12, C13), 126.8 (2 CH arom., C10,11), 145.5 (C quat., arom., C9),
147.5 (C quat., arom., C14), 163.0 (NCHO, C15) ppm. MS (ESI):
m/z = 298.1399. C13H20N3O5 [M + NH4]+ calcd. 298.1403.
(4R,5R)-5-Amino-4-(4-methoxyphenyl)-2,2-dimethyl-1,3-dioxane:[7]
(4R,5R)-5-(Formylamino)-4-(4-methoxyphenyl)-2,2-dimethyl-1,3-
dioxane (0.49 g, 1.84 mmol) was dissolved in aqueous hydrazine
hydrate (85%) (15 mL), and the solution heated under reflux for
3 h. The solution was cooled to room temperature and extracted
with ethyl acetate (3ϫ30 mL). The combined organic extracts were
washed with water (2ϫ30 mL) and brine (2ϫ30 mL), and dried
(Na2SO4), and the solvents were removed under reduced pressure
to give the product as a colourless oil (0.41 g, 95%). [α]2D0 = –39.6
(c = 1.00, CHCl3); [ref.[6] [α]2D0 = –28.9 (c = 1.08, CHCl3)]. IR (film):
νmax = 3372 (NH), 2987, 2937, 1609, 1512, 1458, 1375, 1246, 1192,
(4S,5S)-5-(Formylamino)-2,2-dimethyl-4-[4-(methylthio)phenyl]-1,3-
˜
1
1046, 944, 860, 802 cm–1. H NMR (400 MHz, CDCl3): δ = 1.46 dioxane:[7] Prepared according to the general procedure from
(s, 3 H, CH3, H7 or H8), 1.48 (s, 3 H, CH3, H7 or H8), 2.63 (dd, (1S,2S)-(+)-2-amino-1-(4-methylthiophenyl)-1,3-propandiol (5.00 g,
J = 3.8, 1.8 Hz, 1 H, NCH, H5), 3.74 (s, 3 H, ArOCH3), 3.83 (dd, 23.4 mmol). Colourless oil (5.50 g, 84%). [α]D = +1.3 , c 1.27,
J = 11.7, 1.8 Hz, 1 H, NCHCHH-O, H6), 4.22 (dd, J = 11.7,
2.3 Hz, 1 H, NCHCHH-O, H6Ј), 4.99 (d, J = 1.6 Hz, 1 H, Ar-CH, 1197, 1084, 947. H NMR (250 MHz. CDCl3): δ = 1.54 (s, 3 H),
CHCl ). IR (film): νmax = 3315, 2988, 2362, 1667, 1494, 1380,
˜
3
1
H4), 6.85 (d, J = 8.9 Hz, 2 H, 2 CH arom., H12, H13), 7.18 (d, J
= 8.9 Hz, 2 H, 2 CH arom., H10, H11) ppm. 13C NMR (100 MHz,
CDCl3): δ = 18.6 (CH3, C7 or C8), 29.8 (CH3, C7 or C8), 49.8
1.58 (s, 3 H), 2.45 (s, 3 H), 3.87 (dd, J = 7.5, 1.0 Hz, 1 H), 4.24
(dd, J = 7.5, 1.0 Hz, 1 H), 4.21–4.33 (m, 1 H), 5.16 (d, J = 1.3 Hz,
1 H), 6.27 (d, J = 5.8 Hz, 1 H), 7.20 (s, 4 H), 7.97 (s, 1 H) ppm.
(CH, NCH, C5), 55.3 (CH3, ArOCH3), 66.0 (CH2, C6), 73.5 (Ar- 13C NMR (100 MHz. CDCl3): δ = 15.8, 18.5, 29.7, 45.3, 64.6, 71.4,
CH, C4), 99.2 (C quat., C2), 113.9 (2 CH arom., C10, C11), 126.9
99.7, 125.8, 126.6, 135.0, 137.8, 160.5; MS: m/z = 281.1081.
(2 CH arom., C12, C13), 131.7 (C quat., arom., C9), 158.9 (C quat., C14H19NO3S [M+] calcd. 281.1086 ppm.
Eur. J. Org. Chem. 2009, 3413–3426
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3421

P. C. B. Page, B. R. Buckley, M. M. Farah, A. J. Blacker
FULL PAPER
(4S,5S)-5-(Formylamino)-2,2-dimethyl-4-[4-(methylsulfonyl)phenyl]-
1,3-dioxane:[6] (4S,5S)-5-(Formylamino)-2,2-dimethyl-4-[4-(meth-
ylthio)phenyl]-1,3-dioxane (4.00 g, 14.2 mmol) was dissolved in
dichloromethane (100 mL), and the solution cooled to 0 °C. A
solution of mCPBA (2.2 eq, 7.03 g, 31.0 mmol) in chloroform
(20 mL) was added dropwise over 10 min. The reaction was stirred
for 2 h, washed with saturated aqueous sodium hydrogen carbonate
(2ϫ40 mL) and brine (2ϫ40 mL), and dried (MgSO4). The sol-
vents were removed under reduced pressure to give a colourless oil.
Crystallization from chloroform/diethyl ether gave the product as
a colourless crystalline solid (3.80 g, 85%); m.p. 146–147 °C. [α]D
C12, C13), 147.2 (C quat., arom., C9), 147.3 (C quat., arom., C14)
ppm. MS (FAB): m/z = 253.1186. C12H17N2O4 [M + H]+ calcd.
253.1188.
(4S,5S)-5-Amino-4-(4-aminophenyl)-2,2-dimethyl-1,3-dioxane: Pre-
pared according to the general procedure from (4S,5S)-5-(for-
mylamino)-4-(4-aminophenyl)-2,2-dimethyl-1,3-dioxane
(2.0 g,
7.14 mmol). The product was obtained as a yellow oil (1.55 g,
98%). [α]2D0 = +62.0 (c = 1.13, CHCl ). IR (film): νmax = 3361
˜
3
(NH), 2990, 2939, 1614, 1518, 1380, 1272, 1239, 1198, 1157, 1127,
1
1050, 948, 849, 813 cm–1. H NMR (400 MHz, CDCl3): δ = 1.45
(s, 3 H, CH3, H7 or H8), 1.46 (s, 3 H, CH3, H7 or H8), 2.61 (dd,
J = 2.3, 1.8 Hz, 1 H, NCH, H5), 2.67 (s, 4 H, 4 NH), 3.82 (dd, J
= 12.8, 2.3 Hz, 1 H, NCHCHH-O, H6), 4.19 (dd, J = 12.8, 2.3 Hz,
1 H, NCHCHH-O, H6Ј), 4.93 (d, J = 1.8 Hz, 1 H, Ar-CH, H4),
6.64 (d, J = 8.5 Hz, 2 H, 2 CH arom., H12, H13), 7.03 (d, J =
8.5 Hz, 2 H, 2 CH arom., H10, H11) ppm. 13C NMR (100 MHz,
CDCl3): δ = 18.6 (CH3, C7 or C8), 29.8 (CH3, C7 or C8), 49.7
(CH, NCH, C5), 65.7 (CH2, C6), 73.5 (Ar-CH, C4), 99.2 (C quat.,
C2), 115.1 (2 CH arom., C12, C13), 126.7 (2 CH arom., C10, C11),
129.3 (C quat., arom., C9), 145.8 (C quat., arom., C14) ppm. MS
(FAB): m/z = 223.1445. C12H19N2O2 [M + H]+ calcd. 223.1441.
= –11.6 (c = 1.21, CHCl ). IR (film): νmax = 3054, 2993, 1675,
˜
3
1516, 1382, 1300, 1239, 1202, 1149, 1086, 948 cm–1. C14H19NO5S
(313.37): calcd. C 53.66, H 6.11, N 4.47; found C 52.68, H 6.12, N
4.33. 1H NMR (400 MHz. CDCl3): δ = 1.54 (s, 3 H), 1.57 (s, 3 H),
3.01 (s, 3 H), 3.82 (dd, J = 12.0, 2.0 Hz, 1 H), 4.33 (dd, J = 12.0,
1.6 Hz, 1 H), 4.37 (dd, J = 10.0, 1.6 Hz, 1 H), 5.25 (s, 1 H), 6.51
(d, J = 9.2 Hz, 1 H), 7.52 (d, J = 8.0 Hz, 2 H), 7.85 (d, J = 8.0 Hz,
2 H), 7.89 (s, 1 H) ppm. 13C NMR (100 MHz. CDCl3): δ = 18.9,
29.9, 44.8, 45.4, 64.9, 71.9, 100.4, 127.0, 127.5, 140.0, 145.0, 160.9.
MS: m/z = 314.1058. C14H20NO5S [M++H] calcd. 314.1062 ppm.
General Procedure for the Deprotection of Formamides with Hydraz-
ine Hydrate: The formyl-protected acetonide was dissolved in aque-
ous hydrazine hydrate (85%) (20 mL/g of acetonide) and the solu-
tion heated under reflux for 3 h. The solution was allowed to reach
ambient temperature and extracted with ethyl acetate (3ϫ30 mL/g
of acetonide). The combined organic layers were washed with water
(2ϫ30 mL/g of acetonide) and brine (2ϫ30 mL/g of acetonide),
dried (Na2SO4), and the solvents were removed under reduced pres-
sure.
(4S,5S)-5-Amino-2,2-dimethyl-4-[4-(methylsulfonyl)phenyl]-1,3-di-
oxane:[7] Prepared according to the general procedure from (4S,5S)-
5-(formylamino)-2,2-dimethyl-4-[4-(methylsulfonyl)phenyl]-1,3-di-
oxane (1.80 g, 5.8 mmol), isolated as a colourless oil, and crys-
tallized from diethyl ether/ethyl acetate. Colourless crystals (1.59 g,
96%); m.p. 120–122 °C. [α]2D0
C13H19NO4S (285.36): calcd. C 54.72, H 6.71, N 4.91; found C
= +50.0 (c = 1.00, CHCl3).
54.64, H 6.69, N 4.83. IR (film): νmax = 3372, 2991, 1601, 1380,
˜
1
1198, 1077, 949 cm–1. H NMR (400 MHz, CDCl3): δ = 1.56 (s, 6
H), 2.82–3.00 (m, 1 H), 3.06 (s, 3 H), 3.88 (dd, J = 11.6, 2.0 Hz, 1
H), 3.24 (dd, J = 11.6, 2.4 Hz, 1 H), 5.10–5.19 (m, 1 H), 7.55 (d, J
= 8.0 Hz, 2 H), 7.95 (d, J = 8.0 Hz, 2 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 19.0, 30.0, 44.9, 49.8, 66.8, 73.9, 99.9,
127.2, 127.9, 139.9, 146.6. MS: m/z = 285.1028. C13H19NO4S [M+]
calcd. 285.1035 ppm.
(4S,5S)-5-Amino-2,2-dimethyl-4-phenyl-1,3-dioxane:[19]
according to the general procedure from (4S,5S)-5-(formylamino)-
4-phenyl-2,2-dimethyl-1,3-dioxane (6.58 g, 28.1 mmol). The prod-
uct was isolated as a yellow oil (5.39 g, 87% yield). [α]2D0 = +45.5
Prepared
(c = 2.33, ethanol). IR (film): νmax = 3365 (NH), 2990, 1663, 1498,
˜
1379, 1271, 1239, 1198, 1159, 1130, 1087, 1052, 945, 845, 740, 701
1
cm–1. H NMR (400 MHz, CDCl3): δ = 1.44 (s, 6 H, 2 CH3), 2.64
(4S,5S)-5-Amino-2,2-dimethyl-4-[4-(methylthio)phenyl]-1,3-diox-
ane:[7] Prepared according to the general procedure from (4S,5S)-
5-(formylamino)-2,2-dimethyl-4-[4-(methylthio)phenyl]-1,3-diox-
ane (1.50 g, 5.34 mmol). Colourless oil (1.28 g, 95%). [α]2D0 = +44.7
(dd, J = 4.0, 2.0 Hz, 1 H, NCH, H5), 3.79 (dd, J = 12.0, 2.0 Hz, 1
H, NCHCHH-O, H6), 4.18 (dd, J = 12.0, 2.0 Hz, 1 H, NCHCHH-
O, H6Ј), 4.98 (s, 1 H, PhCH, H4), 7.16–7.29 (m, 5 H, 5 CH arom.,
Ph gp.) ppm. 13C NMR (100 MHz, CDCl3): δ = 18.6 (CH3, C7 or
C8), 29.7 (CH3, C7 or C8), 49.6 (CH, NCH, C5), 65.9 (CH2, C6),
73.7 (Ar-CH, C4), 95.0 (C quat., C2), 125.7 (2 CH arom., C10,
C11), 127.4 (CH arom., C14), 128.4 (2 CH arom., C12, C13), 139.8
(C quat., arom., C9) ppm.
(c = 1.20, CHCl ). IR (film): νmax = 3369, 2990, 1599, 1495, 1379,
˜
3
1198, 1076, 947 cm–1. H NMR (400 MHz, CDCl3): δ = 1.53 (s, 3
1
H), 1.54 (s, 3 H), 2.47 (s, 3 H), 2.72 (q, J = 2.0 Hz, 1 H), 3.88 (dd,
J = 12.0, 2.0 Hz, 1 H), 4.27 (dd, J = 12.0, 2.4 Hz, 1 H), 5.05 (d, J
= 1.6 Hz, 1 H), 7.23–7.28 (m, 4 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 16.0, 18.6, 29.7, 49.6, 66.1, 73.5, 99.2, 126.4, 126.8,
136.6, 137.4. MS: m/z = 253.1137. C13H19NO2S [M+] calcd.
253.1137 ppm.
(4S,5S)-5-Amino-2,2-dimethyl-4-(4-nitrophenyl)-1,3-dioxane:[7] Pre-
pared according to the general procedure from (4S,5S)-5-(for-
mylamino)-2,2-dimethyl-4-(4-nitrophenyl)-1,3-dioxane
(1.00 g,
3.57 mmol) except in that the reaction mixture was heated under
reflux for 1 h. Column chromatography using ethyl acetate as an
eluent gave a yellow oil (0.54 g, 60%). [α]2D0 = +91.6 (c = 0.83,
General Procedure for the Synthesis of Binaphthalene-Derived Imin-
ium Salt Catalysts from (R)- or (S)-2Ј-Bromomethyl-1,1Ј-binaphtha-
lene-2-carboxaldehyde (R)-8 or (S)-8 and Primary Amines: A solu-
tion of the amine in ethanol (10 mL/g of amine) was added drop-
wise to a solution of (R) or (S)-2Ј-bromomethyl-1,1Ј-binaphtha-
CHCl3); [ref.[6] [α]2D0 = +66.2 (c = 1.13, CHCl )]. IR (film): νmax =
˜
3
3373 (NH), 2991, 2939, 1600, 1518, 1380, 1347, 1271, 1239, 1198,
1
1158, 1078, 946, 856 cm–1. H NMR (400 MHz, CDCl3): δ = 1.49 lene-2-carboxaldehyde (R)-8 or (S)-8 (1.10 equiv. wrt amine) in eth-
(s, 6 H, 2 CH3, H7 H8), 2.79 (dd, J = 3.9, 2.0 Hz, 1 H, NCH, H5),
3.81 (dd, J = 12.3, 1.8 Hz, 1 H, NCHCHH-O, H6), 4.26 (dd, J =
anol (10 mL/g of carboxaldehyde) at 40 °C, and the mixture stirred
at 40 °C overnight. The yellowish mixture was cooled to room tem-
12.3, 2.2 Hz, 1 H, NCHCHH-O, H6Ј), 5.12 (d, J = 1.6 Hz, 1 H, perature, and a solution of sodium tetraphenylborate (1.10 equiv.)
Ar-CH, H4), 7.44 (d, J = 10.5 Hz, 2 H, 2 CH arom., H12, H13),
8.16 (d, J = 10.5 Hz, 2 H, 2 CH arom., H10, H11) ppm. 13C NMR
(100 MHz, CDCl3): δ = 18.6 (CH3, C7 or C8), 29.7 (CH3, C7 or
in the minimum amount of acetonitrile added in one portion. The
reaction mixture was stirred for 5 min. The solvents were removed
under reduced pressure, the yellow residue was dissolved in dichlo-
C8), 49.4 (CH, NCH, C5), 66.3 (CH2, C6), 73.4 (Ar-CH, C4), 99.5 romethane (40 mL/g of amine), and the solution washed with water
(C quat., C2), 123.6 (2 CH arom., C10, C11), 126.4 (2 CH arom., (2ϫ30 mL/g of amine) and brine (2ϫ30 mL/g of amine), and dried
3422
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3413–3426

Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
(Na2SO4). The solvents were removed in vacuo. The yellow solid
was recrystallized from ethanol, washed with cold ethanol followed
by hexanes, and dried at 90 °C.
C 78.89, H 5.78, N 1.50. IR (film): νmax = 3050, 2953, 1617, 1532,
˜
1512, 1461, 1376, 1301, 1248, 1203, 1098, 1030, 963, 818, 735 cm–1.
1H NMR (400 MHz, [D6]acetone): δ = 1.70 (s, 3 H, CH3, H7 or
H8), 1.76 (s, 3 H, CH3, H7 or H8), 2.85 (s, 3 H, SO2CH3), 4.30 (d,
J = 13.8 Hz, 1 H, NCHCHHO, H6), 4.42 (d, J = 13.7 Hz, 1 H,
ArCHHN), 4.75 (dd, J = 13.8, 3.2 Hz, 1 H, NCHCHHO, H6Ј),
4.82 (t, J = 3.2 Hz, 1 H, NCH, H5), 6.03 (br. s, 1 H, ArCHHN),
6.06 (d, J = 3.2 Hz, 1 H, ArCH, H4), 6.60–6.64 (m, 4 H, 4 CH
arom., para in BPh4 gp.), 6.87 (t, J = 7.3 Hz, 8 H, 8 CH arom.,
ortho in BPh4 gp.), 6.87 (d, J = 8.7 Hz, 1 H, 2 CH arom., binap),
7.12–7.21 (m, 9 H, CH arom., binap and 8 CH arom., meta in BPh4
gp.), 7.33–7.35 (m, 3 H, 3 CH arom., binap), 7.43 (ddd, J = 8.0,
6.8, 1.2 Hz, 1 H, binap), 7.61–7.69 (m, 5 H, 5 CH arom., binap and
H10, H11, H12, H13), 7.82 (d, J = 8.5 Hz, 1 H, binap), 7.97 (d, J
= 8.3 Hz, 1 H, binap), 8.05 (d, J = 8.4 Hz, 1 H, binap), 8.08 (d, J
= 8.6 Hz, 1 H, binap), 8.14 (d, J = 8.6 Hz, 1 H, binap), 9.06 (s, 1
H, HC=N) ppm. 13C NMR (100 MHz, [D6]acetone): δ = 18.2
(CH3, C7 or C8), 29.1 (CH3, C7 or C8), 43.4 (CH3, SO2CH3), 56.4
(CH2, ArCH2N), 61.1 (CH2, NCHCH2O, C6), 66.9 (CH, NCH,
C5), 71.5 (CH, ArCH, C4), 101.1 (C quat., C2), 121.5 (4 CH arom.,
para in BPh4 gp.), 125.0 (CH arom., binap), 125.1 (CH arom.,
binap), 125.21 (CH arom., binap), 125.26 (8 CH arom., ortho in
BPh4 gp.), 126.0 (C quat., arom.), 126.5 (2 CH arom., C12, C13),
126.8 (CH arom., binap), 127.1 (CH arom., binap), 127.3 (CH
arom., binap), 127.9 (2 CH arom., C10, C11), 128.8 (CH arom.,
binap), 128.9 (CH arom., binap), 129.4 (CH arom., binap), 129.6
(CH arom., binap), 130.6 (CH arom., binap), 131.2 (C quat.,
arom.), 131.4 (C quat., arom.), 131.71 (CH arom., binap), 131.73
(C quat., arom.), 133.9 (C quat., arom.), 135.5 (C quat., arom.),
135.8 (C quat., arom.), 136.2 (8 CH arom., meta in BPh4 gp.), 141.4
(C quat., arom.), 141.8 (C quat., arom.), 142.2 (C quat., arom.),
164.0 (4 C quat., arom., q, J = 49.1 Hz, 4 C-B ipso in BPh4 gp.),
170.6 (HC=N) ppm. MS (ESI): m/z = 562.2044. C35H32NO4S (cat-
ion): calcd. 562.2047.
(Rax)-N-[(4S,5S)-2,2-Dimethyl-4-phenyl-1,3-dioxan-5-yl]-7H-dinaph-
tho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (6): Prepared accord-
ing to the general procedure from (+)-(4S,5S)-5-amino-2,2-di-
methyl-4-phenyl-1,3-dioxane (0.15 g, 0.72 mmol). The product was
isolated as yellow plates (0.39 g, 66 %); m.p. 111–113 °C (dec.).
[α]2D0 = –98.5 (c = 1.04, acetone). C58H50BNO2·1.0H2O: calcd. C
84.73, H 6.13, N 1.71; found C 84.44, H 5.97, N 1.71. IR (film):
νmax = 3055, 2986, 1626, 1610, 1593, 1548, 1478, 1450, 1382, 1266,
˜
1
1203, 1110, 846, 817, 735, 704 cm–1. H NMR (400 MHz, [D6]ace-
tone): δ = 1.79 (s, 3 H), 1.85 (s, 3 H), 4.43 (d, J = 13.2 Hz, 1 H),
4.51 (d, J = 13.6 Hz, 1 H), 4.84–4.88 (m, 2 H), 5.96–6.00 (m, 2 H),
6.76 (t, J = 7.2 Hz, 4 H), 6.93 (t, J = 7.6 Hz, 8 H), 6.95–7.10 (m,
5 H), 7.18–7.32 (m, 2 H), 7.30–7.38 (m, 8 H), 7.41–7.49 (m, 3 H),
7.45–7.65 (m, 2 H), 7.75–7.83 (m, 1 H), 7.88 (d, J = 8.4 Hz, 1 H),
8.10 (d, J = 8.4 Hz, 1 H), 8.17 (d, J = 8.4 Hz, 1 H), 8.23 (dd, J =
8.4, 2.4 Hz, 1 H), 9.29 (s, 1 H) ppm. 13C NMR (100 MHz, [D6]-
acetone): δ = 19.3, 29.7, 57.0, 62.3, 68.4, 72.9, 102.1, 120.5, 122.7,
126.33, 126.4, 126.6, 127.3, 128.1, 128.2, 128.4, 129.1, 129.2, 129.9,
130.0, 130.1, 130.6, 130.7, 131.7, 132.2, 132.6, 132.9, 133.3, 135.3,
136.6, 137.4, 142.8, 165.3, 171.4 ppm. MS (FA+): m/z (%) = 484
(100) [M+], 320 (76), 293 (72), 277 (69), 265 (79), 252 (49), 165 (44),
133 (41). C34H30NO2 (cation): calcd. 484.2271; found 484.2275.
(Sax)-N-[(4R,5R)-2,2-Dimethyl-4-phenyl-1,3-dioxan-5-yl]-7H-dinaph-
tho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (ent-6): Prepared ac-
cording to the general procedure from (–)-(4R,5R)-5-amino-2,2-di-
methyl-4-phenyl-1,3-dioxane (0.16 g, 0.77 mmol). The product was
isolated as yellow plates (0.40 g, 64 %), having almost identical
spectroscopic data to 6; m.p. 109–112 °C (dec.). [α]2D0 = +95.3 (c =
1.01, acetone).
(Sax)-N-[(4S,5S)-2,2-Dimethyl-4-phenyl-1,3-dioxan-5-yl]-7H-dinaph-
tho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate 17:[6] Prepared ac-
cording to the general procedure from (+)-(4S,5S)-5-amino-2,2-di-
methyl-4-phenyl-1,3-dioxane (0.20 g, 0.97 mmol). The product was
(Rax)-N-[(4S,5S)-2,2-Dimethyl-4-(4-nitrophenyl)-1,3-dioxan-5-yl]-
7H-dinaphtho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (18): Pre-
pared according to the general procedure from (4S,5S)-5-amino-
2,2-dimethyl-4-(4-nitrophenyl)-1,3-dioxane (0.40 g, 1.59 mmol).
The product was isolated as a yellow powder (0.93 g, 69%); m.p.
isolated as yellow plates (0.50 g, 64%); m.p. 218 °C (dec.). [α]2D0
=
+360.4 (c = 1.10, acetone). C58H50BNO2·1.0H2O: calcd. C 84.73,
H 6.13, N 1.71; found C 84.33, H 6.06, N 1.64. IR (film): νmax =
˜
144–146 °C (dec.). [α]2D0
C58H49BN2O4·2H2O: calcd. C 78.73, H 6.04, N 3.17; found C
=
–360.0 (c
=
1.00, acetone).
3054, 2998, 1626, 1609, 1579, 1545, 1477, 1458, 1383, 1266, 1201,
1
1110, 840, 817, 733, 704 cm–1. H NMR (250 MHz; [D6]acetone):
78.21, H 5.55, N 3.17. IR (film): νmax = 3052, 2950, 1608, 1523,
˜
δ = 1.72 (s, 3 H), 1.78 (s, 3 H), 4.23 (d, J = 13.4 Hz, 1 H), 4.31 (d,
J = 13.9 Hz, 1 H), 4.73 (dd, J = 13.8, 3.0 Hz, 1 H), 4.90 (br. s, 1
H), 5.35 (d, J = 13.5 Hz, 1 H), 5.86 (d, J = 2.3 Hz, 1 H) 6.76 (t, J
= 7.1 Hz, 4 H), 6.93 (t, J = 7.1 Hz, 8 H), 6.90–6.95 (m, 5 H), 7.17–
7.25 (m, 8 H), 7.26–7.33 (m, 3 H), 7.40–7.48 (m, 1 H), 7.54–7.62
(m, 1 H), 7.72–7.82 (m, 1 H), 7.93 (dd, J = 8.6, 2.2 Hz, 2 H), 8.13
(d, J = 7.9 Hz, 1 H), 8.17 (d, J = 8.4 Hz, 1 H), 8.29 (dd, J = 8.6,
5.3 Hz, 2 H), 9.30 (s, 1 H) ppm. 13C NMR (100 MHz; [D6]acetone):
δ = 19.1, 29.8, 57.3, 61.3, 67.0, 71.5, 100.6, 115.6, 121.9, 125.5,
125.7, 126.5, 126.9, 127.0, 127.3, 127.8, 127.9, 128.1, 128.7, 128.9,
129.3, 129.5, 130.6, 130.9, 131.1, 131.2, 132.0, 133.4, 133.7, 134.4,
141.1, 163.8, 170.8 ppm. MS (FAB+): m/z (%) = 484 (100) [M+],
320 (35), 292 (35), 277 (62), 265 (84), 252 (25), 165 (15), 133 (25).
C34H30NO2 (cation): calcd. 484.2271; found 484.2282.
1461, 1427, 1382, 1348, 1265, 1237, 1201, 1108, 1031, 851, 819,
1
735, 705 cm–1. H NMR (400 MHz, [D3]acetonitrile): δ = 1.72 (s,
3 H, CH3, H7 or H8), 1.82 (s, 3 H, CH3, H7 or H8), 4.36 (d, J =
13.6 Hz, 1 H, NCHCHHO, H6), 4.42 (d, J = 13.3 Hz, 1 H,
ArCHHN), 4.52 (t, J = 2.6 Hz, 1 H, NCH, H5), 4.72 (dd, J = 13.6,
2.6 Hz, 1 H, NCHCHHO, H6Ј), 5.15 (br. s, 1 H, ArCHHN), 5.79
(d, J = 2.6 Hz, 1 H, ArCH, H4), 6.60–6.64 (m, 5 H, CH arom.,
binap and 4 CH arom., para in BPh4 gp.), 7.01 (t, J = 7.3 Hz, 8 H,
8 CH arom., ortho in BPh4 gp.), 7.18 (ddd, J = 8.5, 6.8, 1.3 Hz, 1
H, CH arom., binap), 7.25–7.37 (m, 12 H, 4 CH arom., and 8 CH
arom., meta in BPh4 gp.), 7.45–7.58 (m, 4 H, 4 CH arom.), 7.72–
7.800 (m, 2 H, 2 CH arom.), 7.95 (d, J = 8.1 Hz, 1 H, binap), 8.07
(d, J = 8.4 Hz, 1 H, binap), 8.15 (d, J = 8.8 Hz, 1 H, binap), 8.23
(d, J = 8.6 Hz, 1 H, binap), 9.32 (s, 1 H, HC=N) ppm. 13C NMR
(Rax)-N-[(4S,5S)-2,2-Dimethyl-4-(4-methylsulfonylphenyl)-1,3-di- (100 MHz, [D3]acetonitrile): δ = 17.6 (CH3, C7 or C8), 28.4 (CH3,
oxan-5-yl]-7H-dinaphtho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate
(21): Prepared according to the general procedure from (4S,5S)-5-
C7 or C8), 58.9 (CH2, ArCH2N), 60.8 (CH2, NCHCH2O, C6), 65.3
(CH, NCH, C5), 70.4 (CH, ArCH, C4), 101.0 (C quat., C2), 121.5
amino-4-(4-methylsulfonylphenyl)-2,2-dimethyl-1,3-dioxane (4 CH arom., para in BPh4 gp.), 123.0 (2 CH arom., C12, C13),
(0.54 g, 1.89 mmol). The product was isolated as a yellow powder
(1.08 g, 65%); m.p. 159–163 °C (dec.). [α]2D0 = –283.7 (c = 0.86,
acetone). C59H52BNO4·H2O: calcd. C 78.74, H 6.04, N 1.56; found
124.6 (CH arom., binap), 125.3 (8 CH arom., ortho in BPh4 gp.),
125.6 (C quat., arom.), 125.7 (2 CH arom., C10, C11), 126.2 (CH
arom., binap), 126.7 (CH arom., binap), 126.8 (CH arom., binap),
Eur. J. Org. Chem. 2009, 3413–3426
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3423

P. C. B. Page, B. R. Buckley, M. M. Farah, A. J. Blacker
127.4 (CH arom., binap), 128.1 (CH arom., binap), 128.3 (CH 1.2 Hz, 1 H) 5.06 (q, J = 7.6 Hz, 1 H), 5.48 (d, J = 14.0 Hz, 1 H)
FULL PAPER
arom., binap), 128.9 (CH arom., binap), 129.2 (CH arom., binap),
130.0 (C quat., arom.), 130.3 (CH arom., binap), 131.0 (C quat.,
6.73 (t, J = 8.0 Hz, 4 H), 6.88 (t, J = 8.0 Hz, 8 H), 7.06 (d, J =
8.4 Hz, 1 H), 7.27 (t, J = 8.0 Hz, 8 H), 7.45–7.49 (m, 3 H), 7.56–
arom.), 131.3 (CH arom., binap), 131.6 (C quat., arom.), 133.1 (C 7.63 (m, 1 H), 7.77–7.80 (m, 1 H), 7.99 (d, J = 8.8 Hz, 1 H), 8.03
quat., arom.), 134.1 (C quat., arom.), 134.5 (CH arom., binap), (d, J = 8.4 Hz, 1 H), 8.08 (d, J = 8.4 Hz, 1 H), 8.20 (d, J = 8.4 Hz,
135.1 (C quat., arom.), 135.4 (8 CH arom., meta in BPh4 gp.), 141.5 1 H), 8.26 (d, J = 8.4 Hz, 1 H), 8.31 (d, J = 8.4 Hz, 1 H), 9.62 (s,
(C quat., arom.), 142.5 (C quat., arom.), 146.4 (C quat., arom.), 1 H) ppm. 13C NMR (100 MHz, [D6]acetone): δ = 20.3, 23.9, 28.8,
163.5 (q, J = 49.1 Hz, 4 C quat., arom., 4 C-B ipso in BPh4 gp.),
168.9 (HC=N) ppm.
34.1, 35.2, 40.6, 42.1, 42.6, 48.6, 54.2, 75.6, 122.7, 126.5, 127.2,
127.6, 128.2, 128.3, 128.6, 129.1, 130.0, 130.1, 130.2, 130.6, 130.8,
131.6, 132.8, 132.9, 133.1, 133.3, 135.2, 135.4, 136.7, 137.5, 142.8,
165.4, 170.8 ppm. MS (ES+): m/z = 430 (100) [M+], 355 (30), 154
(15), 119 (13). C32H32N (cation): calcd. 430.2535; found 430.2540.
(Sax)-N-[(4R,5R)-4-(4-Methoxyphenyl)-2,2-dimethyl-1,3-dioxan-5-
yl]-7H-dinaphtho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (20):
Prepared according to the general procedure, method 1, from
(4R,5R)-5-amino-4-(4-methoxyphenyl)-2,2-dimethyl-1,3-dioxane
(0.30 g, 1.26 mmol). The product was isolated as a yellow powder
(0.60 g, 57%); m.p. 199–200 °C (dec.). [α]2D0 = +353.5 (c = 0.86,
acetone). C59H52BNO3: calcd. C 84.98, H 6.29, N 1.68; found C
(+)-(Sax)-N-[(1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl]-
7H-dinaphtho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (23): [6]Pre-
pared according to the general procedure from (–)-isopinocam-
pheylamine (0.25 g, 1.6 mmol). The product was isolated as yellow
plates (0.82 g, 73%), m.p. 225–227 °C (dec). [α]2D0 = +359.1 (c =
1.31, acetone). C48H48BN·0.5H2O: calcd. C 88.61, H 6.91, N 1.85;
84.59, H 6.28, N 1.80. IR (film): νmax = 3053, 2969, 1611, 1548,
˜
1512, 1463, 1379, 1305, 1255, 1201, 1110, 1031, 961, 817, 737, 707,
612 cm–1. 1H NMR (400 MHz, [D6]acetone): δ = 1.79 (s, 3 H, CH3,
H7 or H8), 1.84 (s, 3 H, CH3, H7 or H8), 3.57 (s, 3 H, ArOCH3),
4.41 (d, J = 13.5 Hz, 1 H, NCH-CHH-O, H6), 4.54 (d, J = 13.2 Hz,
1 H, ArCHH-N), 4.64 (t, J = 3.1 Hz, 1 H, NCH, H5), 4.79 (dd, J
= 13.5, 3.1 Hz, 1 H, NCH-CHH-O, H6Ј), 5.87–5.88 (m, 2 H,
ArCH, H4 and ArCHH-N), 6.57 (d, J = 8.7 Hz, 2 H, 2 CH arom.,
H12, H13), 6.74–6.79 (m, 4 H, 4 CH arom., para in BPh4 gp.), 6.92
(t, J = 7.2 Hz, 8 H, 8 CH arom., ortho in BPh4 gp.), 7.00 (d, J =
8.7 Hz, 1 H, CH arom., binap), 7.19 (d, J = 8.7 Hz, 2 H, 2 CH
arom., H10, H11), 7.27–7.31 (m, 1 H, CH arom., binap), 7.33–7.37
(m, 8 H, 8 CH arom., meta in BPh4 gp.), 7.43–7.49 (m, 2 H, 2 CH
arom., binap), 7.53–7.61 (m, 2 H, 2 CH arom., binap), 7.77–7.83
(m, 2 H, 2 CH arom., binap), 8.11 (dd, J = 8.2, 0.6 Hz, 1 H, CH
arom., binap), 8.20 (dd, J = 8.4, 0.8 Hz, 1 H, CH arom., binap),
8.23 (d, J = 8.6 Hz, 1 H, CH arom., binap), 8.26 (d, J = 8.6 Hz, 1
H, CH arom., binap), 9.09 (s, 1 H, HC=N) ppm. 13C NMR
(100 MHz, [D6]acetone): δ = 18.9 (CH3, C7 or C8), 29.9 (CH3, C7
or C8), 55.5 (CH3, ArOCH3), 58.2 (CH2, ArCH2N), 61.9 (CH2,
NCH-CH2-O, C6), 68.3 (CH, NCH, C5), 72.4 (CH, ArCH, C4),
101.6 (C quat., C2), 114.8 (2 CH arom., C12, C13), 122.3 (4 CH
arom., para in BPh4 gp.), 126.1 (8 CH arom., ortho in BPh4 gp.),
126.3 (2 CH arom., C10, C11), 127.1 (C quat., arom., binap-2),
127.2 (2 CH arom., binap), 127.7 (CH arom., binap), 127.8 (CH
arom., binap), 128.1 (CH arom., binap), 128.7 (CH arom., binap),
128.9 (C quat., arom., C9), 129.65 (CH arom., binap), 129.70 (CH
arom., binap), 130.2 (CH arom., binap), 130.3 (CH arom., binap),
131.4 (CH arom., binap), 131.8 (C quat., arom., binap-10), 132.2
(C quat., arom., binap-5Ј), 132.5 (CH arom., binap), 132.8 (C quat.,
arom., binap-10Ј), 134.8 (C quat., arom., binap-5), 136.3 (C quat.,
arom., binap-2Ј), 136.5 (C quat., arom., binap-1Ј), 137.1 (8 CH
arom., meta in BPh4 gp.), 142.5 (C quat., arom., binap-1), 160.4 (C
quat., arom., C14), 164.9 (4 C quat., arom., q, J = 49.1 Hz, 4 C-B
ipso in BPh4 gp.), 170.7 (HC=N) ppm. MS (ESI): m/z = 514.2386.
C35H32NO3 (cation): calcd. 514.2377.
found C 88.38, H 6.86, N 1.80.IR (nujol): ν = 3053, 2996, 1627,
˜
1
1610, 1580, 1549, 1206, 750, 705 cm–1. H NMR (400 MHz, [D6]-
acetone): δ = 0.84 (d, J = 4.0 Hz, 3 H), 1.13 (s, 3 H), 1.32 (s, 3 H),
1.51 (d, J = 8.0 Hz, 1 H), 2.00–2.08 (m, 1 H), 2.13–2.23 (m, 1 H)
2.31–2.39 (m, 1 H), 2.64–2.71 (m, 1 H), 2.75–2.81 (m, 2 H), 4.80
(dd, J = 13.6, 1.2 Hz, 1 H) 5.14 (q, J = 7.6 Hz, 1 H), 5.50 (d, J =
14.0 Hz, 1 H) 6.74 (t, J = 8.0 Hz, 4 H), 6.89 (t, J = 8.0 Hz, 8 H),
7.06 (d, J = 8.4 Hz, 1 H), 7.33 (t, J = 8.0 Hz, 8 H), 7.40–7.51 (m,
3 H), 7.72–7.76 (m, 1 H), 7.77–7.80 (m, 1 H), 7.94 (d, J = 8.8 Hz,
1 H), 7.99 (d, J = 8.4 Hz, 1 H), 8.08 (d, J = 8.4 Hz, 1 H), 8.20 (d,
J = 8.4 Hz, 1 H), 8.24 (d, J = 8.4 Hz, 1 H), 8.29 (d, J = 8.4 Hz, 1
H), 9.72 (s, 1 H) ppm. 13C NMR (100 MHz, [D6]acetone): δ = 19.4,
23.4, 28.5, 33.8, 35.1, 40.2, 41.6, 42.3, 48.2, 54.7, 75.4, 122.2, 125.9,
126.0, 126.0, 126.1, 126.1, 126.4, 127.8, 127.9, 128.00, 128.0, 128.1,
128.6, 129.5, 129.6, 130.2, 130.3, 131.2, 132.3, 137.0, 137.1, 142.4,
164.9, 171.2 ppm. MS (FAB+): m/z = 430 (100) [M+], 294 (55), 277
(52), 265 (61), 263 (32), 252 (20).C32H32N (cation): calcd. 430.2535;
found 430.2536.
Representative Epoxidation Procedure: Oxone (0.77 g, 1.26 mmol)
was added to an ice-cooled solution of sodium carbonate (0.26 g,
2.52 mmol) in water (2.1 mL) with stirring, and the resulting foam-
ing solution stirred for 5–10 min, so that most of the initial effer-
vescence subsided. A solution of the iminium salt 6 (0.5 mol-%,
0.0025 g, 0.0032 mmol) in acetonitrile (1.05 mL) was added, fol-
lowed by a solution of 1-phenylcyclohexene (0.10 g, 0.63 mmol) in
acetonitrile (1.05 mL). The suspension was stirred until the sub-
strate was completely consumed by TLC (2.0 h). The reaction mix-
ture was diluted with ice-cooled diethyl ether (20 mL), immediately
followed by the addition of water (20 mL). The aqueous phase was
extracted with diethyl ether (4ϫ20 mL) and the combined organic
extracts were washed with brine and dried (MgSO4). Filtration and
evaporation of the solvents furnished a light brown residue. Col-
umn chromatography, eluting with ethyl acetate/light petroleum
(1:99) afforded pure 1-phenylcyclohexene oxide as a colourless oil
(–)-(Rax)-N-[(1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl]-
7H-dinaphtho[2,1-c;1Ј,2Ј-e]azepinium Tetraphenylborate (22):[6] Pre-
pared according to the general procedure from (–)-isopinocam-
pheylamine (0.25 g, 1.6 mmol). The product was isolated as yellow
plates (0.82 g, 73%), m.p. 219–221 °C (dec). [α]2D0 = –318.8 (c =
1.37, acetone). C48H48BN·0.5H2O: calcd. C 88.61, H 6.91, N 1.85;
[0.071 g, 65%, 91% ee, (–)-1S,2S]. Colourless oil. IR (neat): νmax
˜
= 3084, 1602, 1495, 1446, 1359, 1249, 1173, 1132, 1079, 1030, 993,
974 cm–1. 1H NMR (250 MHz, CDCl3): δ = 1.22–1.35 (m, 1 H),
1.53–1.64 (3H m), 1.99–2.06 (m, 2 H) 2.16–2.18 (m, 1 H), 2.26–
2.32 (m, 1 H), 3.10 (t, J = 2.0 Hz, 1 H), 7.28–7.44 (m, 5 H) ppm.
13C NMR (62.5 MHz, CDCl3): δ = 19.8, 20.1, 24.7, 28.2, 60.1, 61.8,
125.3, 127.1, 128.2, 142.8 ppm.
found C 88.22, H 6.81, N 1.79. IR (nujol): ν = 3055, 2997, 1629,
˜
1
1612, 1588, 1551, 1155, 818, 734, 706 cm–1. H NMR (400 MHz,
[D6]acetone): δ = 1.10 (s, 3 H), 1.21 (d, J = 6.8 Hz, 3 H), 1.32 (s, 3
trans-Stilbene Oxide:[6,20] Colourless solid. IR (nujol): ν = 1601,
˜
H), 1.53 (d, J = 10.4 Hz, 1 H), 2.01–2.08 (m, 1 H), 2.15–2.17 (m, 1492, 1284, 1176, 1157, 1094, 1072, 1025 cm–1. 1H NMR
1 H) 2.39–2.45 (m, 1 H), 2.63–2.70 (m, 3 H), 4.80 (dd, J = 13.6,
(400 MHz, CDCl3): δ = 3.84 (s, 2 H), 7.28–7.37 (m, 10 H) ppm.
3424
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3413–3426

Binaphthalene-Derived Iminium Salt Epoxidation Catalysts
13C NMR (100 MHz, CDCl3): δ = 63.3, 126.0, 128.6, 129.3, 137.6
ppm.
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1,2-Dihydronaphthalene Oxide:[6,21] Colourless oil. IR (neat): νmax
˜
= 3059, 3028, 2930, 2850, 1602, 1493, 1316, 1129, 1088, 1030, 964
1
cm–1. H NMR (400 MHz, CDCl3): δ = 1.65–1.73 (m, 1 H), 2.30–
2.36 (m, 1 H), 2.45 (dd, J = 15.6, 5.6 Hz, 1 H), 2.67–2.74 (m, 1 H),
3.65 (t, J = 4.0 Hz, 1 H), 3.78 (d, J = 4.4 Hz, 1 H), 7.01 (d, J =
7.2 Hz, 1 H), 7.10–7.20 (m, 2 H), 7.33 (d, J = 7.2 Hz, 1 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 22.2, 24.8, 55.2, 55.6, 126.5,
128.8, 128.8, 129.9, 132.9, 137.1 ppm.
1-Phenylcyclohept-1-ene Oxide:[6,22] Colourless oil. IR (neat): νmax
˜
= 3084, 1602, 1494, 1445, 1358, 1255, 1166, 1128, 1088, 1030, 964,
1
855, 738 cm–1. H NMR (250 MHz, CDCl3): δ = 1.50–1.85 (m, 6
H), 1.90–2.20 (m, 2 H), 2.38–2.50 (m, 2 H), 3.04 (q, J = 3.8 Hz, 1
H), 7.25–7.40 (m, 5 H) ppm. 13C NMR (62.5 MHz, CDCl3): δ =
24.9, 25.5, 29.9, 31.7, 33.9, 63.4, 65.8, 125.4, 127.3, 128.5, 142.0
ppm.
trans(α-Methyl)stilbene Oxide:[6,23] Colourless oil. IR (neat): νmax
˜
= 3061, 1602, 1495, 1449, 1381, 1279, 1157, 1118, 1065, 1027, 980
cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.46 (s, 3 H), 3.96 (s, 1 H),
7.30–7.46 (m, 10 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 17.1,
63.5, 67.5, 125.6, 126.9, 127.7, 127.9, 128.6, 129.2, 136.4, 142.8
ppm.
Triphenylethylene Oxide:[6,24] Colourless oil which slowly solidified.
IR (neat): νmax = 3062, 3030, 2957, 2925, 2856, 1605, 1596, 1499,
˜
[3]
[4]
1
1471, 1448, 1262, 1221, 741, 698, 621 cm–1. H NMR (250 MHz,
CDCl3): δ = 4.40 (s, 1 H), 7.10–7.47 (m, 15 H) ppm. 13C NMR
(62.5 MHz, CDCl3): δ = 68.0, 68.3, 126.3, 126.8, 127.5, 127.6,
127.7, 127.8 128.0, 128.2, 128.6, 135.42, 135.9, 141.1 ppm.
1-Phenyl-3,4-dihydronaphthalene Oxide:[6,25] Pale yellow solid. IR
(nujol): ν = 1602, 1486, 1307, 1155, 1074, 1042, 953 cm–1. 1H NMR
˜
(250 MHz, CDCl3): δ = 2.10 (td, J = 5.8, 13.7 Hz, 1 H), 2.49–2.60
(m, 1 H), 2.77 (dd, J = 5.6, 15.5 Hz, 1 H), 2.98–3.06 (m, 1 H), 3.71
(d, J = 3.1 Hz, 1 H), 7.11–7.31 (m, 4 H), 7.45–7.61 (m, 5 H) ppm.
13C NMR (62.5 MHz, CDCl3): δ = 22.1, 25.4, 60.9, 63.0, 126.0,
127.7, 127.9, 128.1, 128.2, 128.6, 129.8, 135.0, 137.5, 138.8 ppm.
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Acknowledgments
This investigation has enjoyed the support of Loughborough Uni-
versity, the Engineering and Physical Sciences Research Council
(EPSRC), and NPIL Pharmaceuticals (UK) Ltd. We acknowledge
the support of the Royal Society of Chemistry (RSC) (Industry
Fellowship to P. C. B. P.). We are also indebted to the EPSRC Mass
Spectrometry Unit, Swansea.
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3413–3426