"Instant methylide" modification of the Corey-Chaykovsky cyclopropanation reaction

Article abstract of DOI:10.1080/00397910500521837

Treatment of various electron-deficient alkenes in DMSO with stable, dry, equimolar mixtures of either Me₃S(O)I/KOt-Bu or Me ₃S(O)I/NaH cleanly afforded the corresponding substituted cyclopropanes in good yields and short reaction ti

Full text of DOI:10.1080/00397910500521837

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“Instant Methylide” Modification of the
Corey–Chaykovsky Cyclopropanation Reaction
James A. Ciaccio a & Courtney E. Aman a
a Department of Chemistry , Fordham University , Bronx, New York, USA
Published online: 16 Aug 2006.
To cite this article: James A. Ciaccio & Courtney E. Aman (2006) “Instant Methylide” Modification of the
Corey–Chaykovsky Cyclopropanation Reaction, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 36:10, 1333-1341
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Synthetic Communicationsw, 36: 1333–1341, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910500521837
“Instant Methylide” Modification
of the Corey–Chaykovsky
Cyclopropanation Reaction
James A. Ciaccio and Courtney E. Aman
Department of Chemistry, Fordham University, Bronx, New York, USA
Abstract: Treatment of various electron-deficient alkenes in DMSO with stable, dry,
equimolar mixtures of either Me3S(O)I/KOt-Bu or Me3S(O)I/NaH cleanly afforded
the corresponding substituted cyclopropanes in good yields and short reaction times
(,20 min for reactions at 50–608C using 0.4–4.0 mmol alkene).
Keywords: Corey–Chaykovsky reactions, cyclopropanation, methylide, MIRC reaction
Cyclopropanes often serve as synthetic building blocks[1] leading to more
functionalized alicyclic and acyclic compounds as a result of the relative
ease by which they ring-open under a variety of conditions.[1d,2] A number
of natural products and biologically active compounds contain cyclopropane
rings,[3] and this rigid carbocyclic system has been used to restrict the confor-
mation of biologically active compounds to improve their activity.[4]
Cyclopropanes are commonly synthesized from alkenes by (1) halomethyl-
metal-mediated cyclopropanation reactions (e.g., Simmons–Smith reaction),[5]
(2) transition metal–catalyzed carbene transfer from aliphatic diazo
compounds,[6] and (3) a Michael-type nucleophilic addition–ring closure
sequence (Michael-initiated ring closure, MIRC),[7] usually involving conjugate
addition to electron-deficient alkenes by a nucleophile possessing a leaving group.
Received in the USA October 25, 2005
Address correspondence to James A. Ciaccio, Department of Chemistry, Fordham
University, Bronx, New York, USA. Tel.: 718-817-4441; Fax: 718-817-4432; E-mail:
ciaccio@fordham.edu
1333

1334
J. A. Ciaccio and C. E. Aman
One of the most effective classes of MIRC reagents for methylene transfer
are heteroatom-derived ylides, and the reaction of dimethylsulfoxonium
methylide (Corey’s reagent, DMSY, Me2S(O)55CH2)[8] with a,b-unsaturated
ketones (Corey–Chaykovsky cyclopropanation)[9] is one of the most straight-
forward and oft-cited cyclopropanation reactions; the resulting cyclopropyl
ketones are synthetically useful[10] and often serve as internal mechanistic
probes for single-electron-transfer (SET) reactions.[11] Standard conditions
for Corey–Chaykovsky cyclopropanation usually involve preforming
dimethylsulfoxonium methylide (DMSY) by treating trimethylsulfoxonium
iodide (Me3S(O)I) with NaH in dimethyl sulfoxide (DMSO) for 20 min–2 h,
followed by addition of the enone and heating the mixture to 508C for
2 h.[9,12] A number of modifications have been reported, including the use of
phase-transfer conditions,[13] ionic solvents,[14] and external asymmetric
ligands to induce chirality in the product.[15]
We recently reported[16] that sulfoxonium and sulfonium methylides
formed upon treatment of storable, dry, 1 : 1 mixtures of Me3S(O)I/KOt-Bu
and Me3SI/NaH, respectively, with carbonyl compounds in DMSO con-
veniently and rapidly afforded the corresponding epoxides by an “instant
methylide” modification of the Corey–Chaykovsky epoxidation, reminiscent
of the Schlosser–Schaub “instant ylide” modification of Wittig olefination,
which uses storable alkyltriphenylphosphonium salt–base mixtures.[17] We
now report that treatment of various electron-deficient alkenes in DMSO
with storable, dry, 1 : 1 mixtures of Me3S(O)I/KOt-Bu or Me3S(O)I/NaH
conveniently and rapidly affords the corresponding substituted cyclopropanes
by an “instant methylide” modification of the Corey–Chaykovsky cyclopro-
panation reaction (Scheme 1, Table 1).
Reaction of both enolizable and nonenolizable substrates (1a–h) in
DMSO with either Me3S(O)I/KOt-Bu or Me3S(O)I/NaH afforded the corre-
sponding cyclopropanes (2a–h) in good yield (avg. yield shown in the table is
80%), and the crude products generally were pure enough to be used directly
for further reactions, as determined by TLC and 13C and 1H NMR analyses. In
most cases, TLC analysis of reactions performed at 50–608C with either
Me3S(O)I/KOt-Bu or Me3S(O)I/NaH indicated the complete consumption
of starting substrate (0.4–4.0 mmol) within 15 min.
Scheme 1. R1 ¼ acyl, aroyl, CO2t-Bu, NO2; R2 ¼ H or alkyl; R3 ¼ H or aryl; R4 ¼ H
or alkyl; base ¼ KOt-Bu or NaH.

Table 1. Reaction conditions for cyclopropane synthesis using “instant methylide” salt–base mixtures
Me3S(O)I/KOt-
Bu, room temp:
Me3S(O)I/KOt-
Bu, 50–608C:
Me3S(O)I/NaH,
room temp:
Me3S(O)I/NaH,
50–608C: Yield,
% (time, h)c
Compound
Alkene substratea
Prod. no.b
Yield, % (time, h) Yield, % (time, h)c Yield, % (time, h)
1a
2a
88 (0.75)
85 (1)
80 (0.25)
97 (0.25)
60 (0.50)
87 (1)
93 (0.50)
96 (0.25)
1b
2b
1c
2c
68 (0.50)
66 (0.58)
70 (0.25)d
99 (0.25)
61 (0.50)
80 (0.50)
74 (0.25)d
98 (0.25)
1d
2de
1e
2e
93 (0.50)
90 (0.25)f
95 (1)
90 (0.25)
(continued)

Table 1. Continued
Me3S(O)I/KOt-
Bu, room temp:
Me3S(O)I/KOt-
Bu, 50–608C:
Me3S(O)I/NaH,
room temp:
Me3S(O)I/NaH,
50–608C: Yield,
% (time, h)c
Compound
Alkene substratea
Prod. no.b
Yield, % (time, h) Yield, % (time, h)c Yield, % (time, h)
1f
2f
67 (0.67)
72 (0.25)
86 (0.83)
83 (0.25)
1g
1h
2g
2h
—
—
71 (0.25)
57 (0.25)
—
—
68 (0.25)
55 (0.25)
aSubstrate–methylide molar ratio ¼ 1 : 1.2 (1 : 2.2 for 1d; 1 : 2.5 for 1g using Me3S(O)I/KOt-Bu; 1 : 3 for 1g using Me3S(O)I/NaH).
bYields are for isolated products using 0.4–1.4 mmol alkene substrate, except where indicated.
cReactions run at 50–608C were complete within 15 min, according to TLC analysis.
dFor reactions of 1c run at 50–608C, the sulfoxonium salt–base mixture was heated for 10–15 min at 50–608C in DMSO prior to addition of 1c to
avoid the formation of a minor amount of an unidentified side product.
eObtained as an approximately 1 : 1 mixture of diastereomers, according to NMR analysis.
fResult using 1.0 g (4.0 mmol) of 1e.

“Instant Methylide” Cyclopropanation
1337
The method is experimentally straightforward: a DMSO solution of
alkene substrate is combined with an appropriate amount of sulfoxonium
salt–base mixture (molar ratio of substrate–methylide ¼ 1 : 1.2 for simple
enones), and the resulting mixture is either maintained at room temperature
for 1 h or less or heated to nearly 608C for approx. 15 min, followed by
treatment with brine and an ether-extractive workup.
These “instant methylide” modifications of the Corey–Chaykovsky
reactions offer a quick, convenient, and experimentally simple preparation
of either disubstituted epoxides[16] or suitably substituted cyclopropanes,
with advantages over conventional procedures: ease of handling (the
mixture of sulfoxonium salt and base can be stored indefinitely under
anhydrous conditions without significant loss of activity), methylides are
generated in the presence of substrate in nearly all cases, and reaction
times are relatively short (,20 min when Me3S(O)I/KOt-Bu is used at
50–608C to convert nonconjugated ketones to epoxides and when either
Me3S(O)I/KOt-Bu or Me3S(O)I/NaH is used at 50–608C for conversion
of electron-deficient alkenes to cyclopropanes). Preliminary results suggest
that “instant methylide” aziridination of suitably substituted imines is
possible.
EXPERIMENTAL
Reactions with NaH were performed using glassware that was oven-dried
at 1208C. All solvents, reagents, and alkene substrates (except 1e)[18] are
commercially available. Analytical TLC was performed using hard-layer
silica-gel GHLF Uniplates with inorganic binder (Analtech, Inc.) and
Riedel-deHaen TLC plates, silica gel (60 F 254) of 0.2-mm thickness on
aluminum (available from Aldrich Chem. Co.). Plates were visualized by
UV, I2, and/or 10% phosphomolybdic acid in absolute ethanol. 1H
spectra were recorded at 300 MHz and 13C spectra were recorded at
75 MHz on a Bruker AvanceTM DPX300 spectrometer with the use of
CDCl3 as solvent. Chemical shifts were measured relative to internal
TMS. Cyclopropanes 2a–d and 2f–h (Table 1) have been reported pre-
viously, and our spectral data are in agreement with the published data.
Cyclopropane 2e, a viscous oil, was converted to its corresponding 2,4-
dinitrophenylhydrazone, and this solid derivative provided acceptable
combustion elemental analysis data (performed by Quantitative Technol-
ogies Inc., Whitehouse, NJ).
Preparation of the Sulfoxonium Salt and Base Mixtures
Appropriate amounts of powdered Me3S(O)I and the base were thoroughly
mixed, placed in screw-cap glass (amber) bottles, and then stored in

1338
J. A. Ciaccio and C. E. Aman
desiccators with no significant loss in activity for samples stored for more
than 1 yr:
Me3S(O)I (5.90 g; 26.8 mmol) þ KOt-Bu (3.00 g; 26.7 mmol) ¼ 3.0 mmol
methylide/g,
Me3S(O)I (5.00 g; 22.7 mmol) þ NaH (dry; 0.545 g; 22.7 mmol) ¼ 4.1 mmol
methylide/g.
General Procedure for Cyclopropane Synthesis
An anhyd. DMSO (6–8 mL) solution of the alkene substrate (0.4–4.0 mmol)
was added all at once to a dry mixture of either Me3S(O)I/KOt-Bu or
Me3S(O)I/NaH (1.2 molar equivalents for 1a–c, 1e, 1f, 1h; 2.2 equivalents
for 1d; 2.5 or 3 equivalents for 1g) in a small, round-bottomed flask at
room temperature. The resulting clear solution was stirred for either 15–
30 min while the flask was immersed in an oil or water bath heated to 50–
608C or for 0.5–1 h at room temperature (or until TLC analysis revealed
the absence of alkene substrate). The mixture was then treated with brine
(50 mL) and extracted with diethyl ether (2 ꢀ 30 mL). The combined
organic extracts were washed successively with water (2 ꢀ 50 mL) and
brine (1 ꢀ 50 mL), dried over anhyd. MgSO4, filtered, and evaporated in
vacuo to afford the corresponding cyclopropane.
Data
trans-Phenyl(2-phenylcyclopropyl)methanone (2a).[19] 1H NMR d 7.98
(m, 2H), 7.60–7.10 (m, 8H), 2.90 (m, 1H), 2.70 (m, 1H), 1.93 (m, 1H),
1.55 (m, 1H). 13C NMR d 198.46, 140.40, 137.63, 132.84, 128.49, 128.04,
126.53, 126.15, 29.94, 29.23, 19.19.
trans-[2-(4-Methoxyphenyl)cyclopropyl]phenylmethanone (2b).[20] 1H
NMR d 7.97 (m, 2H), 7.57–7.40 (m, 3H), 7.10 (d, J ¼ 8.6 Hz, 2H), 6.85
(d, J ¼ 8.6 Hz, 2H). 13C NMR d 198.49, 158.31, 137.65, 132.72, 132.29,
128.42, 127.95, 127.26, 113.69, 55.17, 29.55, 29.09, 18.83.
trans-1-(2-Phenylcyclopropyl)ethanone (2c).[21] 1H NMR d 7.30–7.05
(m, 5H), 2.50 (m 1H), 2.29 (s, 3H), 2.20 (m, 1H), 1.65 (m, 1H), 1.35
(m, 1H). 13C NMR d 206.68, 140.14, 128.34, 126.36, 125.86, 32.72, 30.17,
28.86, 18.98.
trans, trans-bis(2-Phenylcyclopropyl)methanone (2d, approx. 1 : 1
mixture of diastereomers).[22] 1H NMR d 7.30–7.05 (m, 10H), 2.58
(m, 2H), 2.35 (m, 2H), 1.74 (m, 2H), 1.40 (m, 2H). 13C NMR d 206.95,
206.86, 140.33, 140.23, 128.39, 128.25, 126.42, 125.96, 125.92, 33.25,
33.07, 29.25, 29.04, 19.39, 19.25.

“Instant Methylide” Cyclopropanation
1339
trans-1,3-Benzodioxol-5-yl(2-phenylcyclopropyl)methanone (2e). 1H
NMR d 7.60 (d, 1H), 7.45 (s, 1H), 7.30–7.10 (m, 5H), 7.15 (d, 1H), 6.80
(d, 1H), 5.98 (d, 2H), 2.80 (m, 1H), 2.65 (m, 1H), 1.90 (m, 1H), 1.50
(m, 1H). 13C NMR d 196.29, 151.57, 148.05, 140.45, 132.42, 128.43,
126.43, 126.08, 124.25, 107.73, 101.71, 29.50, 28.88, 17.91.
2,4-Dinitrophenylhydrazone derivative of 2e: m.p. 220–2218C (recrystal-
1
lized from CH3CN). H NMR d 11.99 (s, 1H), 9.15 (d, J ¼ 2.4 Hz, 1H),
8.35 (dd, J ¼ 2.4, 9.6 Hz, 1H), 8.10 (d, J ¼ 9.6 Hz, 1H), 7.45–7.15
(m, 7H), 6.83 (d, J ¼ 8.3 Hz, 1H), 6.05 (s, 2H), 2.25 (m, 1H), 2.05 (m, 1H),
1.89 (m, 1H), 1.40 (m, 1H). 13C NMR d 153.94, 149.31, 148.04, 144.47,
139.70, 138.10, 130.44, 129.97, 129.73, 128.91, 126.91, 125.59, 123.56,
122.69, 116.70, 108.10, 107.18, 101.56, 24.77, 19.94, 16.61. Anal. calcd.
for C23H18N4O6: C, 61.88; H, 4.06; N, 12.55. Found: C, 61.59; H, 3.80; N,
12.48.
(1S,4S)-1-Methyl-4-(1-methylethenyl)bicyclo[4.1.0]heptan-2-one (2f)[12,23]
(Prepared from (S)-(þ)-carvone). 1H NMR d 4.75 (m, 2H), 2.47–2.31 (m, 2H),
2.12–1.80 (m, 3H), 1.70 (s, 3H), 1.57 (m, 1H), 1.36 (m, 1H), 1.24 (s, 3H), 0.86
(m, 1H). 13C NMR d 209.99, 146.81, 109.57, 41.60, 36.48, 29.02, 26.74, 25.03,
20.32, 19.52, 17.47.
t-Butyl trans-2-phenylcyclopropanecarboxylate (2g).[24] 1H NMR d 7.30–
7.02 (m, 5H), 2.43 (m, 1H), 1.83 (m, 1H), 1.52 (m, 1H), 1.46 (s, 9H), 1.23
(m, 1H). 13C NMR d 172.50, 140.39, 128.33, 126.23, 125.98, 80.46, 28.07,
25.65, 25.19, 16.94.
trans-(2-Nitrocyclopropyl)benzene (2h).[25] 1H NMR d 7.40–6.90 (m, 5H),
4.31 (m, 1H), 3.05 (m, 1H), 2.15 (m, 1H), 1.55 (m, 1H). 13C NMR d 136.22,
128.72, 127.59, 126.54, 61.55, 29.31, 18.69.
ACKNOWLEDGMENTS
We are grateful for the generous financial support provided by the Fordham
University Clare Boothe Luce Undergraduate Scholars Program (support for
C. E. A.), Research Corporation Cottrell College Science Award No.
C-3698, and the National Science Foundation’s Division of Undergraduate
Education through Grant DUE #9650684.
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