The preparation of N-tert-butyloxycarbonyl-(Boc-)protected sulfoximines and sulfimines by an iron(II)-mediated nitrene transfer from BocN3 to sulfoxides and sulfides

Article abstract of DOI:10.1002/(SICI)1099-0690(199905)1999:5<1033::AID-EJOC1033>3.0.CO;2-1

The imidation of sulfides and sulfoxides to the corresponding sulfimides and sulfoximides was carried out with N-tert-butyloxycarbonyl azide (BocN₃) in the presence of FeCl₂. Sulfoxides 1 reacted at room temperature in CH₂

Full text of DOI:10.1002/(SICI)1099-0690(199905)1999:5<1033::AID-EJOC1033>3.0.CO;2-1

FULL PAPER
The Preparation of N-tert-Butyloxycarbonyl-(Boc-)Protected Sulfoximines
and Sulfimines by an Iron(II)-Mediated Nitrene Transfer from BocN3
to Sulfoxides and Sulfides
Thorsten Bach*[a] and Christina Körber[a]
Keywords: Homogenous catalysis / Iron / Imidation / Sulfur / Synthetic methods
The imidation of sulfides and sulfoxides to the corresponding
sulfimides and sulfoximides was carried out with N-tert-
butyloxycarbonyl azide (BocN3) in the presence of FeCl2.
Sulfoxides 1 reacted at room temperature in CH2Cl2 to give
the corresponding sulfoximides 3 in 40–95% yield. The
imidation of the sterically congested substrate tert-butyl
methyl sulfoxide (1f) proceeded sluggishly (10% yield). The
sterospecificity of the reaction was demonstrated with the
intermediate (nitrene)FeIV complex is postulated as the
reactive nitrene transfer reagent which is formed from FeCl2
and BocN3. The more nucleophilic sulfides 2 reacted more
readily in the imidation than sulfoxides. Their conversion to
the corresponding sulfimides 4 was conducted with BocN3
and a substoichiometric amount of FeCl2 (0.25 equiv.). Yields
ranged between 44 and 92%. In an alternative reaction
mode, BocN3 was utilized at 0°C in the presence of FeCl2
enantiomerically enriched substrates (R)-(+)-1b and (S)-(–)- and acetyl acetone. The sulfimidation, which did not
1d which yielded the sulfoximides (R)-(+)-3b and (S)-(–)-3d
with retention of configuration. Mechanistically, an
otherwise occur at this temperature, was accelerated by the
ligand (36–90% yield).
The transfer of a nitrene fragment to sulfur compounds quantities. There were several reasons why this type of reac-
leads to the corresponding N-substituted imides. Starting tion appeared interesting to us. First of all, the nitrene
from sulfoxides sulfoximides[1] of the general structure A transfer to sulfur nucleophiles is mechanistically related to
are accessible, whereas sulfides yield sulfimides[2] B (Scheme the nitrene tranfer to alkenes (aziridination).[24] Conditions
1). Various reagents have been employed to achieve this found for a successful imidation of sulfur compounds might
transformation. Prominent examples include the transfer of hint at possible procedures for olefin aziridinations. The
“NTs” (Ts ϭ p-toluenesulfonyl) from TsN3,[3][4] chloramine same notion holds good for mechanistic details and for in-
T,[3e,5,6] or PhIϭNTs,[7][8] of “NH” from HN3,[3f,9] or O- termediate (nitrene)metal complexes involved in these reac-
mesitylsulfonyl hydroxylamine (MSH),[10][11] and of “N- tions. Secondly, the Boc group was assumed to be readily
alkyl” from a primary amine in the presence of an oxi- cleaved (vide infra),[25] so the free sulfoximines would be
dant[12][13] to name some known methods.[14][15]
accessible by a mild method. If the imidation proceeded
stereospecifically, enantiomerically pure N-Boc-protected
sulfoximines and unprotected sulfoximines could be synthe-
sized from enantiomerically pure sulfoxides. Thirdly, a new
stereogenic center is established in the course of the sulfide
imidation. If a suitable metal-based catalyst system for ra-
cemic sulfimide formation could be devised, an enantiose-
lective variant would be conceivable by modifying the li-
gand or the counterion of the metal involved.[26]
Scheme 1. General strategy for the imidation of sulfur compounds
to sulfoximides A and sulfimides B
Sulfides and sulfoxides have comparably rarely been con-
verted into their N-alkoxycarbonyl-substituted imide de-
rivatives. Most procedures employed for this purpose utilize
alkoxycarbonyl azides[16][17] from which the nitrene frag-
ment is liberated thermally or photochemically.[4a,18] Tran-
sition-metal-mediated processes of this type are not
known.[19][20] N-Chloro- and N-trifluormethanesulfonyl-
oxy-substituted carbamates have been used for the imida-
tion of sulfides.[21]
Empirically, we have recently found that FeCl2 is a useful
promoter for the aforementioned nitrene transfer to sulfur
compounds (Equation a).[27]
Some time ago, we wondered whether the transfer of an
N-tert-butyloxycarbonyl-protected nitrene fragment from
[22]
the readily available BocN3
(Boc ϭ N-tert-butyloxycar-
bonyl) (Caution!)[23] might be possible in the presence of a
promoter, which would ideally be used in substoichiometric
In the following account we report on the details of this
method. It was demonstrated that the N-Boc imidation of
sulfoxides proceeds stereospecifically under retention of
configuration. Moreover, the ligand-accelerated imidation
of sulfides to N-Boc-substituted sulfimines is described.
[a]
Fachbereich Chemie, Philipps-Universität Marburg,
D-35032 Marburg, Germany
Fax: (internat.) ϩ 49(0)6421/288917
E-mail: bach@chemie.uni-marburg.de
Eur. J. Org. Chem. 1999, 1033Ϫ1039
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ193X/99/0505Ϫ1033 $ 17.50ϩ.50/0
1033

T. Bach, C. Körber
FULL PAPER
Reaction with Sulfoxides
Preliminary experiments were carried out in order to
identify possible transition metal compounds which induce
the dediazotization of BocN3. Upon treatment of BocN3 (1
equiv.) with FeCl2 (1 equiv.) in a polar solvent such as ace-
tone or DMF at ambient temperature a gas evolution was
observed. The color of the solution changed from yellow to
a reddish brown and O-tert-butyl carbamate (BocNH2) was
isolated as the major reaction product after workup. Run-
ning the same reaction in DMSO as the solvent gave the
sulfoximide 3a in 58% yield. Lowering the amount of FeCl2
to 25 mol-% (0.25 equiv.) led to a small deterioration in
yield (55%).
Table 1. The FeII-catalyzed imidation of sulfoxide 1d with tert-but-
yloxycarbonyl azide according to Equation b
Entry 1d (equiv.) FeCl2 (equiv.) Conditions
Yield (%)[a]
1
2
3
4
5
6
7
8
5
1
0°C Ǟ r.t.
0°C Ǟ r.t.
0°C Ǟ r.t.
0°C Ǟ r.t.
r.t.
70
58
65
56
29
26
28
28
2.5
2.5
2.5
2.5
2.5
2.5
2.5
1
0.5
0.25
1
1
0°C Ǟ r.t.[b]
0°C Ǟ r.t.[c]
0°C Ǟ r.t.[d]
1
0.5
[a]
[b]
Yield of isolated product. Ϫ Reaction conducted under aero-
[c]
[d]
bic conditions. Ϫ
addition of the sulfoxide.
Terminal addition of BocN3. Ϫ
Terminal
conditions (entry 6), or if the the mode of reagent addition
was changed (entries 7 and 8).
This result is in contrast to the thermal reaction of alk-
oxycarbonyl azides in which a significant degree of nitrene
transfer was observed only at elevated temperatures.[4a,16] In
control experiments performed with DMSO and BocN3 at
room temperature there was no detectable formation of
compound 3a, indicating that the iron salt induces the ni-
trene transfer. A series of experiments in which other metal
salts {Mn(OAc)2, MnBr2, FeSO4, FeCl3, Fe3(PO4)2,
K4[Fe(CN)6], RuCl3, Co(OAc)2, Rh2(OAc)4, RhCl3,
Ni(OAc)2, CuCl, CuI, CuCl2, Cu(OAc)2, AgOAc, ZnCl2,
SnCl4} were tested revealed that FeCl2 is particularly well
suited for this purpose. The Lewis acidity appears to be a
minor factor for the efficiency of the reaction, as com-
pounds either more or less Lewis acidic (vide supra) than
FeCl2 did not induce a significant decomposition of BocN3.
FeCl3 is unreactive, which clearly points to the importance
of redox processes involved. For a more detailed study di-
rected at an optimization of the reaction conditions the
imidation of benzyl methyl sulfoxide (1d) was selected,
which was run in degassed CH2Cl2 as the solvent (Equation
b, Table 1). Pre-mixing of the starting materials at 0°C un-
der argon and subsequent addition of FeCl2 resulted in an
evolution of nitrogen and the previously described color
change. Upon warming to ambient temperature the reac-
tion proceeded to completion and the product was isolated
in analytically pure form after column chromatography.
The behavior of other sulfoxides with regard to a varia-
tion of reaction conditions was similar to what had been
observed with sulfoxide 1d but it was not studied systemati-
cally. Table 2 provides an overview about the reactions we
have conducted with an array of substrates. Yields were in
general moderate to good except for tert-butyl methyl sulf-
oxide (1f, entry 6), in which case the steric hindrance of the
tert-butyl group apparently prohibits an approach of the
nitrogen electrophile to the nucleophilic sulfur atom.
Table 2. The FeII-mediated imidation of various sulfoxides 1 with
tert-butyloxycarbonyl azide according to Equation a in CH2Cl2 as
the solvent
Entry
Sulfoxide
R
R1
Product Yield (%)[a]
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1e
1f
Me
Ph
Me
Me
Me
Me
Me
Me
Et
3a
3b
3c
3d
3e
3f
58
74
84
70
54
10
95
40
An[b]
Bn
iPr
tBu
Bn
1g
1h
3g
3h
Bn
Ph
[a]
[b]
Yield of isolated product. Ϫ An ϭ Anisyl.
The removal of the Boc group proceeded uneventfully[25]
With a large excess of sulfoxide (5 equiv.) the yield was as was already alluded to in the introduction. By this means
good (entry 1). free sulfoximines are readily available. An example for a
Lowering the amount of sulfoxide used led to a decrease successful deprotection is depicted in Scheme 2. In order
in product formation (entry 2). A decrease in the catalyst to investigate the stereochemical outcome of the sulfoxide
concentration proved to have a minor influence, and the imidation we prepared the sulfoxide (R)-(ϩ)-1b in enantio-
yield remained approximately constant if more than 0.25 merically enriched form (84% ee) by the Ti-based oxidation
equiv. FeCl2 relative to BocN3 were used (entries 3 and 4). of sulfide 2b.[28] After the nitrogen transfer had been carried
Further lowering either the ratio of sulfoxide/BocN3 or the out in the usual manner, sulfoximide (R)-(Ϫ)-3b was ana-
amount of FeCl2 relative to BocN3 led to a decline of the lyzed by chiral HPLC (Daicel Chiracel OD). Both enantio-
reaction rate. Similarly, the increase of the initial tempera- mers were identified by comparison with racemic material.
ture (entry 5) had a negative influence on the yield. Lower Integration of the baseline-separated peaks revealed an en-
yields were recorded if the reaction was run under aerobic antiomeric excess of 85% which secured the stereospecificity
1034
Eur. J. Org. Chem. 1999, 1033Ϫ1039

N-tert-Butyloxycarbonyl-(Boc-)Protected Sulfoximines and Sulfimines
FULL PAPER
of the reaction. After deprotection to sulfoximine (R)-(Ϫ)- µ-imido complex formation should be essentially irrevers-
5b the comparison of the specific optical rotation with the ible and it accounts for the loss of catalytic activity. Further
value reported for (S)-(ϩ)-5b[10b] proved that the nitrene experiments are under way to further prove the described
transfer had occurred with retention of configuration. Simi- hypothesis.
larly, the imidation of sulfoxide (S)-(Ϫ)-1d was shown to
proceed stereospecifically. The reaction delivered the corre-
sponding sulfoximide (S)-(Ϫ)-3d without deterioration of
the enantiomeric excess (62% ee). Subsequent deprotection
gave the free sulfoximine (S)-(Ϫ)-5d in 72% yield (see Ex-
Reaction with Sulfides
perimental Section).
If the nucleophilicity of the sulfur compound is indeed
important to guarantee a fast nitrene transfer from an Fe
intermediate whose alternate reaction pathway is the forma-
tion of a (µ-imido)FeIII complex, it was expected that sulf-
ides would be more efficient in the imidation reaction. At
0°C, however, no reaction was observed upon mixing vari-
ous sulfides with BocN3 and FeCl2 in CH2Cl2. The iron salt
did not dissolve and the solution remained almost colorless.
Upon warming to room temperature, the reaction com-
menced and the usual gas evolution was observed. A 1:1:0.5
ratio of sulfide/BocN3/FeCl2 was identified as ideal for an
effective nitrene transfer. The results for several sulfides are
summarized in Table 3.
Scheme 2. Stereospecific imidation of enantiomerically enriched
[a]
sulfoxides and subsequent deprotection; the deprotection proce-
dure was not optimized (see Experimental Section)
Although the azide was the limiting agent in these reac-
tions it is important to note that the nitrene transfer pro-
ceeded almost quantitatively with regard to sulfoxide con-
version. The non-converted chiral sulfoxide (R)-(ϩ)-1b for
example was fully recovered from the reaction mixture with
no deterioration of the optical purity. The yield based on
sulfoxide conversion was determined to be > 80% for most
cases.
Mechanistic investigations lag behind the preparative
experiments we have carried out so far. As mentioned pre-
viously it is very likely that a redox process is involved in
the nitrene transfer we studied. If no sulfoxide was added,
the major reaction product derived from BocN3 was
BocNH2 (vide supra) and an oxidation of FeII was indicated
by the color change of the reaction mixture. This assump-
tion is in accord with the lower yield which was recorded if
Table 3. The FeII-catalyzed imidation of various sulfides 2 with
tert-butyloxycarbonyl azide according to Equation a in CH2Cl2 as
the solvent
Entry
Sulfide
R
R1
Product Yield (%)[a]
1
2
3
4
5
6
7
2a
2b
2d
2e
2f
2g
2h
Me
Ph
Bn
iPr
tBu
Bn
Bn
Me
Me
Me
Me
Me
Et
4a[b]
4b
4d
4e
27
82
87
44
6
90
92
4f
4g
4h
Ph
[a] Yield of isolated product. Ϫ [b] Not stable upon chromatography.
In contrast to the sulfoxide system an excess of the sulfur
the reaction was run under aerobic conditions (entry 6, nucleophile is not neccessary for a good conversion. This
Table 1). In an earlier report[29] it was revealed that aryl result reflects the higher reactivity of sulfides, which allows
azides undergo a reaction with FeII compounds to yield the them to compete more successfully than sulfoxides against
corresponding (µ-imido)FeIII complexes. The hydrolysis of the FeII nucleophile in the reaction with the putative (ni-
a similar complex derived from BocN3 would yield BocNH2 trene)FeIV complex. The amount of catalyst could be low-
upon hydrolysis and could therefore readily account for the ered to 0.1 equiv. without a significant reduction in yield,
formation of this product. Although we have not yet been provided a higher sulfide/BocN3 ratio was chosen. Again,
able to isolate a putative µ-N-Boc-imido complex we postu- as in the sulfoxide case, a bulky substituent at the sulfur
late its intermediacy based on the above-mentioned anal- atom strongly inhibits attack of the nitrene transfer reagent
ogy. The µ-imido complex is most likely a sluggish nitrene (sulfide 2f, entry 5). Dimethyl sulfide (2a) reacted cleanly
transfer reagent in agreement with the observation that the but the resulting sulfimide 4a proved to be unstable and
terminal addition of sulfoxide 1d to a premixed solution of could not be purified by chromatography.
BocN3 and FeCl2 was inferior to the normal addition mode
Attempts to induce a reaction at 0°C were initiated in
(entry 8, Table 1). We therefore speculate that a precursor order to find possible ligands which solubilize the FeII salt
to such a µ-imido complex is responsible for the nitrene and, by this means, accelerate the reaction. For these experi-
transfer. A (nitrene)FeIV complex[30] is a conceivable inter- ments a 2.5:1:0.25 ratio of sulfide/BocN3/FeCl2 was found
mediate, which is either attacked by the sulfur nucleophile most suitable. After some unsuccessful trials (among others
to yield the sulfoximide or by FeII to yield the µ-imido com- using sulfimides as possible ligands) DMF[27] and acetyl
plex. Whereas FeII is regenerated upon sulfoxide attack, the acetone emerged as ideal candidates for the desired pur-
Eur. J. Org. Chem. 1999, 1033Ϫ1039
1035

T. Bach, C. Körber
FULL PAPER
Dichloromethane was distilled from calcium hydride under Ar.
Common solvents (tert-butyl methyl ether, pentane, and methanol)
were distilled prior to use. BocN3,[22][23] the sulfoxides 1bϪ1h,[32]
and the sulfides 2b, 2dϪ2g[33] were prepared according to literature
procedures. All other reagents and solvents were used as received.
Ϫ Melting points (uncorrected): Reichert hot bench. Ϫ IR: Bruker
IFS 88 FT-IR or Nicolet 510 M FT-IR. Ϫ MS: Varian CH7 (EI).
Ϫ GC: Hewlett-Packard HP 6890 series GC systems, column HP-
1 (crosslinked methyl siloxane, 30 m). Ϫ 1H and 13C NMR: Bruker
ARX-200, Bruker AC-300, Bruker AM-400, Bruker HMX-500.
Chemical shifts are reported relative to tetramethylsilane as an in-
ternal reference. CDCl3 was used unless noted otherwise. Ϫ El-
emental analysis: Varian Elementar vario EL. Ϫ TLC: Merck alu-
minium sheets (0.2 mm silica gel 60 F254), a pentane/tert-butyl
methyl ether mixture was used; detection by UV or by coloration
with ceric ammonium molybdate (CAM). Ϫ Column chromatogra-
phy: Merck silica gel 60 (70Ϫ230 mesh).
pose. Acetyl acetone was superior in most cases and Table
4 provides the results obtained with this ligand.
Table 4. Catalysis of the imidation of various sulfides 2 with tert-
butyloxycarbonyl azide by FeCl2/acetyl acetone according to Equa-
[a]
tion c Yield of isolated product.
Entry
Sulfide
R
R1
Product Yield (%)[a]
1
2
3
4
5
6
2b
2d
2e
2f
2g
2h
Ph
Bn
iPr
tBu
Bn
Bn
Me
Me
Me
Me
Et
4b
4d
4e
4f
4g
4h
90
61
36
4
67
57
Benzyl N-tert-Butyloxycarbonyl Methyl Sulfoximine (3d). ؊ Typical
Procedure A: 1 mmol of BocN3 (143 mg) and 5 mmol of benzyl
methyl sulfoxide[32a] (1d) (780 mg) were dissolved in 0.75 mL of
dry CH2Cl2 at 0°C. After addition of 1 mmol of FeCl2 (126 mg)
nitrogen started to evolve. The reaction mixture was warmed to
room temperature and stirred overnight. It was subsequently
poured into 5 mL of water and the aqueous layer was extracted
with CH2Cl2 (5 ϫ 3 mL). The combined organic layers were
washed with water and dried with MgSO4. After filtration, the sol-
vent was removed and the residue was purified by column chroma-
tography (pentane/tert-butyl methyl ether, 20:80). 188 mg (70%) of
3d was obtained as a white solid. Rf ϭ 0.35 (tert-butyl methyl
ether). Ϫ M.p. 62Ϫ64°C. Ϫ IR (KBr): ν˜ ϭ 1659 cmϪ1 (w, CϭO),
1285 (s, CϪOϪC), 1174 (s, CϪOϪC). Ϫ 1H NMR (300 MHz):
Ph
[a] Yield of isolated product. Ϫ [b] Not stable upon chromatography.
As the ligand had to be removed by chromatography the
reaction of dimethyl sulfide (2a) was not studied. Except
for sulfimide 4f the sulfimide yields are moderate to good.
The synthetically interesting sulfimide 4b, which should be
suited as a methylene transfer reagent,[31] was formed in
excellent yield. Based on these results work is currently in
progress aimed at chiral ligands that can induce an enantio-
selective nitrene transfer to sulfides.
2
δ ϭ 1.67 [s, 9 H, C(CH3)3], 3.07 (s, 3 H, SCH3), 4.87 (d, J ϭ 14.2
2
Hz, 1 H, CHH), 4.97 (d, J ϭ 14.0 Hz, 1 H, CHH), 7.57 (s, 5 H,
Summary and Conclusion
arom. H). Ϫ 13C NMR (75.5 MHz): δ ϭ 28.1 [C(CH3)3], 37.9
(SCH3), 59.4 (SCH2), 80.5 [C(CH3)3], 127.6 (arom. C), 129.2 (arom.
C), 129.5 (arom. C), 130.8 (arom. C), 158.5 (CϭO). Ϫ MS (70
eV); m/z (%): 213 (67) [C9H11NO3Sϩ], 154 (18)[C8H10OSϩ] 91 (100)
[C7H7ϩ], 57 (33) [C4H9ϩ]. Ϫ C13H19NO3S (269.35): calcd. C 57.97,
H 7.11, N 5.20; found C 57.73, H 7.35, N 5.09.
N-Boc-substituted sulfoximides and sulfimides were syn-
thesized by an FeCl2-promoted nitrene transfer to sulf-
oxides and sulfides in CH2Cl2 as the solvent. In order to
ensure a reasonable nitrene transfer an excess sulfoxide was
required. The mass balance with regard to sulfoxide was
very good and unchanged sulfoxide was fully recovered
without significant losses. The conversion of sulfoxides into
sulfoximides proceeded stereospecifically under retention of
configuration. The removal of the Boc group was facile and
sulfoximines were readily available. A (nitrene)FeIV complex
is postulated as an intermediate in these reactions, whose
attack by a sulfoxide yields the corresponding sulfoximide
whereas an attack by solvated FeCl2 yields a (µ-imido)FeIII
complex. The latter complex is assumed to be catalytically
inactive and yields BocNH2 upon hydrolysis. The more nu-
cleophilic sulfides reacted more readily in the nitrene trans-
fer reaction than sulfoxides. A 1:1 ratio of sulfide/BocN3
was satisfactory to ensure moderate to good yields in the
presence of 0.5 equiv. FeCl2 at room temperature. It was
shown that the addition of a suitable ligand facilitates a
nitrene transfer at 0°C presumably by coordinating to FeCl2
and thus solubilizing it in CH2Cl2
(S)-(؊)-Benzyl N-tert-Butyloxycarbonyl Methyl Sulfoximine (3d):
Enantiomerically enriched (62% ee) material was prepared accord-
ing to procedure A from (S)-(Ϫ)-benzyl methyl sulfoxide[28] (1d).
25
Ϫ [α]D ϭ Ϫ50.7 (c ϭ 1.1, acetone).
(S)-(؊)-Benzyl Methyl Sulfoximine (5d): The enantiomerically en-
riched sulfoximide (S)-(Ϫ)-3d (0.65 mmol, 177 mg) was treated with
0.5 mL of CF3COOH in 3 mL of CH2Cl2 at 0°C. The mixture was
warmed to room temperature and the volatiles were removed by
azeotropic distillation with toluene. The residue was dissolved in
water and neutralized with aqueous Na2CO3 solution. The aqueous
layer was extracted with CH2Cl2 (4 ϫ 4 mL). The combined or-
ganic layers were dried with MgSO4. Upon removal of the solvent
25
80 mg of (S)-(Ϫ)-5d (72%) remained. Ϫ [α]D ϭ Ϫ7.6 (c ϭ 0.9,
acetone). Ϫ All other analytical data are identical to those reported
in the literature for racemic 5d.[10c]
N-tert-Butyloxycarbonyl Dimethyl Sulfoximine (3a):[16] The reac-
tion was carried out as described in typical procedure A starting
from dimethyl sulfoxide (1a). 102 mg (58%) of 3a was obtained as
a white solid. The analytical data were in full agreement with those
reported in the literature.[16a]
Experimental Section
General: All reactions involving water-sensitive chemicals were car-
N-tert-Butyloxycarbonyl Methyl Phenyl Sulfoximine (3b): The reac-
tion was carried out as described in typical procedure A starting
from methyl phenyl sulfoxide[32a] (1b). 188 mg (74%) of 3b was
ried out in flame-dried glassware with magnetic stirring under Ar.
1036
Eur. J. Org. Chem. 1999, 1033Ϫ1039

N-tert-Butyloxycarbonyl-(Boc-)Protected Sulfoximines and Sulfimines
FULL PAPER
obtained as a white solid. Ϫ Rf ϭ 0.26 (tert-butyl methyl ether). Ϫ
M.p. 65Ϫ67°C. Ϫ IR (KBr): ν˜ ϭ 1666 cmϪ1 (s, CϭO), 1278 (s,
CϪOϪC), 1159 (s, CϪOϪC), 748 (s, CϪS). Ϫ 1H NMR (200
MHz): δ ϭ 1.35 [s, 9 H, C(CH3)3], 3.21 (s, 3 H, SCH3), 7.49Ϫ7.66
(m, 3 H, arom. H). 7.87Ϫ7.96 (m, 2 H, arom. H). Ϫ 13C NMR (50
MHz): δ ϭ 27.6 [C(CH3)3], 44.3 (SCH3), 80.2 [C(CH3)3], 127.0
(arom. C), 129.2 (arom. C), 132.4 (arom. C), 138.5 (arom. C), 157.1
(CϭO). Ϫ MS (70 eV); m/z (%): 182 (9) [C8H8NO2Sϩ], 140 (11)
[C7H8SOϩ], 77 (22) [C6H5ϩ], 56 (45) [C4H8ϩ]. Ϫ C12H17NO3S
(255.33): calcd. C 56.45, H 6.71, N 5.48; found C 56.45, H 6.81,
N 5.41.
[C6H12NOSϩ], 57 (100) [C4H9ϩ]. Ϫ C10H21NO2S (235.35): calcd.
C 51.03, H 8.99, N 5.95; found C 50.89, H 8.63, N 5.66.
Benzyl N-tert-Butyloxycarbonyl Ethyl Sulfoximine (3g): The reac-
tion was carried out as described in typical procedure A starting
from benzyl ethyl sulfoxide[32a] (1g). 268 mg (95%) of 3g was ob-
tained as a white solid. Ϫ Rf ϭ 0.47 (tert-butyl methyl ether). Ϫ
M.p. 107Ϫ109°C. Ϫ IR (KBr): ν˜ ϭ 1643 cmϪ1 (s, CϭO), 1276 (s,
1
CϪOϪC), 1159 (s, CϪOϪC), 884 (s, SϪN), 797 (s, SϪN). Ϫ H
3
NMR (200 MHz): δ ϭ 1.32 (t, J ϭ 7.5 Hz, 3 H, CH2CH3) 1.47
[s, 9 H, C(CH3)3], 3.02 (q, 3J ϭ 7.5 Hz, 2 H, CH2CH3), 4.64 (d,
2J ϭ 14.3 Hz, 1 H, CHH), 4.78 (d, 2J ϭ 14.3 Hz, 1 H, CHH), 7.36
(s, 5 H, arom. H). Ϫ 13C NMR (50 MHz): δ ϭ 6.3 (CH2CH3), 28.1
[C(CH3)3], 44.3 (CH2CH3), 56.6 (CH2Ph), 80.3 [C(CH3)3], 125.6
(arom. C), 129.0 (arom. C), 129.1 (arom. C), 130.4 (arom. C), 158.7
(CϭO). Ϫ MS (70 eV); m/z (%): 227 (16) [C10H13NO3Sϩ], 91 (100)
[C7H7ϩ], 57 (40) [C4H9ϩ], 29 (9) [C2H5ϩ]. Ϫ C14H21NO3S (283.39):
calcd. C 59.34, H 7.47, N 4.94; found C 59.08, H 7.55, N 4.73.
(R)-(؊)-N-tert-Butyloxycarbonyl Methyl Phenyl Sulfoximine (3b):
Enantiomerically enriched (85% ee) material was prepared accord-
ing to procedure A from (R)-(ϩ)-methyl phenyl sulfoxide[28] (1b).
25
Ϫ [α]D ϭ Ϫ52.9 (c ϭ 1.0, acetone).
(R)-(؊)-Methyl Phenyl Sulfoximine (5b): The sulfoximine was ob-
tained from (R)-(Ϫ)-3b in 63% yield following the procedure de-
25
Benzyl N-tert-Butyloxycarbonyl Phenyl Sulfoximine (3h): The reac-
tion was carried out as described in typical procedure A starting
from benzyl phenyl sulfoxide[32b] (1h). 132 mg (40%) of 3h was
obtained as a white solid. Ϫ Rf ϭ 0.67 (tert-butyl methyl ether). Ϫ
M.p. 102°C. Ϫ IR (KBr): ν˜ ϭ 1665 cmϪ1 (s, CϭO), 1285 (s,
CϪOϪC), 1169 (s, CϪOϪC), 754 (s, CϪS), 689 (s, CϪS). Ϫ 1H
NMR (200 MHz): δ ϭ 1.36 [s, 9 H, C(CH3)3], 4.63 (s, 1 H, CH2Ph),
6.85Ϫ6.89 (m, 2 H, arom. H), 7.08Ϫ7.23 (m, 3 H, arom. H),
7.49Ϫ7.60 (m, 3 H, arom. H), 7.33Ϫ7.40 (m, 2 H, arom. H). Ϫ 13C
NMR (50 MHz): δ ϭ 28.1 [C(CH3)3], 62.1 (CH2Ph), 80.6
[C(CH3)3], 127.1 (arom. C), 128.5 (arom. C), 128.7 (arom. C), 129.0
(arom. C), 129.1 (arom. C), 131.2 (arom. C), 133.7 (arom. C), 135.5
(arom. C), 158.0 (CϭO). Ϫ MS (70 eV); m/z (%): 275 (10)
[C14H13NO3Sϩ], 91 (100) [C7H7ϩ], 77 (29) [C6H5ϩ], 57 (60)
[C4H9ϩ].
scribed for (S)-(Ϫ)-5d above. Ϫ [α]D ϭ Ϫ28.1 (c ϭ 1.2, acetone).
25
Ϫ The value reported for (S)-(ϩ)-5b (93.5% ee)[10b] is [α]D
ϭ
ϩ34.1 (c ϭ 2.0, acetone). All other analytical data are identical to
those reported in the literature for racemic 5b.[10c]
N-tert-Butyloxycarbonyl 4-Methoxyphenyl Methyl Sulfoximine (3c):
The reaction was carried out as described in typical procedure A
starting from 4-methoxyphenyl methyl sulfoxide[32a] (1c). 239 mg
(84%) of 3c was obtained as a white solid. Ϫ Rf ϭ 0.19 (tert-butyl
methyl ether). Ϫ M.p. 106Ϫ108°C. Ϫ IR (KBr): ν˜ ϭ 1665 cmϪ1 (s,
CϭO), 1274 (s, CϪOϪAr), 1251 (s, CϪOϪC), 1157 (s, CϪOϪC).
1
Ϫ H NMR (200 MHz): δ ϭ 1.27 [s, 9 H, C(CH3)3], 3.12 (s, 3 H,
3
SCH3), 3.77 (s, 3 H, OCH3), 6.96 (d, J ϭ 9.0 Hz,2 H, arom. H),
3
7.80 (d, J ϭ 9.0 Hz, 2 H, arom. H). Ϫ 13C NMR (50 MHz): δ ϭ
28.0 [C(CH3)3], 45.1 (SCH3), 55.7 (OCH3), 80.3 [C(CH3)3], 114.8
(arom. C), 129.5 (arom. C), 129.6 (arom. C), 157.7 (arom. C), 163.7
(CϭO). Ϫ MS (70 eV); m/z (%): 212 (53) [C9H10NO3Sϩ], 170 (18)
[C8H10SOϩ], 107 (13) [C7H8Oϩ], 57 (47) [C4H9ϩ]. Ϫ C13H19NO4S
(285.36): calcd. C 54.47, H 6.71, N 4.91; found C 54.45, H 6.51,
N 4.68.
Benzyl N-tert-Butyloxycarbonyl Methyl Sulfimine (4d). ؊ Typical
Procedure B: 1 mmol of BocN3 (143 mg) and 1 mmol of benzyl
methyl sulfide[33a] (2d) (140 mg) were dissolved in 0.75 mL of dry
CH2Cl2. After addition of 0.5 mmol of FeCl2 (67 mg), nitrogen
started to evolve and the mixture was stirred overnight at room
temperature. The reaction mixture was poured into 5 mL of water
and the aqueous layer was extracted with CH2Cl2 (5 ϫ 3 mL). The
combined organic layers were washed with water and were dried
with MgSO4. After filtration, the solvent was removed and the resi-
due was purified by column chromatography (CH2Cl2/methanol,
100:0 Ǟ 80:20). 220 mg (87%) of 4d was obtained as a colorless
oil which crystallized upon standing. Ϫ Rf ϭ 0.21 (CH2Cl2/meth-
anol, 98:2). Ϫ M.p. 55Ϫ56°C. Ϫ IR (KBr): ν˜ ϭ 1616 cmϪ1 (s, Cϭ
O), 1287 (s, CϪOϪC), 1159 (s, CϪOϪC), 698 (s, CϪS). Ϫ 1H
NMR(300 MHz): δ ϭ 1.51 [s, 9 H, C(CH3)3], 2.50 (s, 3 H, SCH3),
4.02 (d, 2J ϭ 12.7 Hz, 1 H, CHH), 4.44 (d, 2J ϭ 12.7 Hz, 1 H,
CHH), 7.32Ϫ7.44 (m, 5 H, arom. H). Ϫ 13C NMR (75.5 MHz):
δ ϭ 28.1 [C(CH3)3], 28.5 (SCH3), 53.0 (CH2Ph), 78.3 [C(CH3)3],
128.3 (arom. C), 128.7 (arom. C), 128.8 (arom. C), 129.9 (arom.
N-tert-Butyloxycarbonyl Isopropyl Methyl Sulfoximine (3e): The re-
action was carried out as described in typical procedure A starting
from isopropyl methyl sulfoxide[32a] (1e). 119 mg (54%) of 3e was
obtained as a white solid. Ϫ Rf ϭ 0.22 (tert-butyl methyl ether). Ϫ
M.p. 50°C. Ϫ IR (KBr): ν˜ ϭ 1657 cmϪ1 (s, CϭO), 1274 (s,
CϪOϪC), 1171 (s, CϪOϪC), 789 (s, CϪS), 763 (s, CϪS). Ϫ 1H
3
NMR (200 MHz): δ ϭ 1.38 (d, J ϭ 6.8 Hz, 3 H, CH3CHCH3),
1.40 (d, 3J ϭ 6.8 Hz, 3 H, CH3CHCH3), 1.40 [s, 9 H, C(CH3)3],
3
3.00 (s, 3 H, SCH3), 3.55 (sept, J ϭ 6.8 Hz, 1 H, CH3CHCH3). Ϫ
13C NMR (50 MHz): δ ϭ 15.3 (CH3CHCH3), 15.9 (CH3CHCH3),
26.8 (SCH3), 28.0 [C(CH3)3], 54.5 (CH3CHCH3), 80.0 [C(CH3)3],
158.6 (CϭO). Ϫ MS (70 eV); m/z (%): 148 (24) [C5H10NO2Sϩ], 106
(50) [C4H10Sϩ], 57 (57) [C4H9ϩ], 43 (87) [C3H7ϩ]. Ϫ C9H19NO3S
(221.32): calcd. C 48.84, H 8.65, N 6.33; found C 48.73, H 8.55,
N 6.15.
C), 164.2 (CϭO). Ϫ MS (70 eV); m/z (%): 253 (0.1) [Mϩ
ϭ
C13H19NO2Sϩ], 91 (100) [C7H7ϩ], 57 (36) [C4H9ϩ]. Ϫ C13H19NO2S
(253.53): calcd. C 61.63, H 7.56, N 5.53; found C 61.54, H 7.52,
N 5.51.
tert-Butyl N-tert-Butyloxycarbonyl Methyl Sulfoximine (3f): The re-
action was carried out as described in typical procedure A starting
from tert-butyl methyl sulfoxide[32a] (1f). 24 mg (10%) of 3f of was
obtained as a colorless oil. Ϫ Rf ϭ 0.31 (tert-butyl methyl ether).
N-tert-Butyloxycarbonyl Dimethyl Sulfimine (4a): The reaction was
Ϫ IR (film): ν˜ ϭ 1722 cmϪ1 (s, CϭO), 1241 (s, CϪOϪC), 1191 (s, carried out as described in typical procedure B starting from di-
CϪOϪC), 721 (s, CϪS). Ϫ 1H NMR (300 MHz): δ ϭ 1.47 [s, 9 methyl sulfide (2a). 47 mg (27%) of 4a was obtained as a white
1
H, SC(CH3)3], 1.48 [s, 9 H, OC(CH3)3], 3.20 (s, 3 H, SCH3). Ϫ
13C NMR (50 MHz): δ ϭ 23.6 [SC(CH3)3], 28.7 [OC(CH3)3], 33.0
[SC(CH3)3], 60.7 (SCH3), 80.4 [OC(CH3)3], 160.0 (CϭO). Ϫ MS
solid. Ϫ Rf ϭ 0.12 (CH2Cl2/methanol, 98:2). Ϫ M.p. 70°C. Ϫ H
NMR (200 MHz): δ ϭ 1.39 [s, 9 H, C(CH3)3], 1.59 (s, 6 H, SCH3).
Ϫ
13C NMR (75.5 MHz): δ ϭ 28.3 [C(CH3)3], 33.1 (SCH3), 78.7
(70 eV); m/z (%): 236 (0.4) [Mϩ ϭ C10H21NO3Sϩ], 136 (34) [C(CH3)3], 164.5 (CϭO). Ϫ MS (70 eV); m/z (%): 177 (0.2) [Mϩ
ϭ
Eur. J. Org. Chem. 1999, 1033Ϫ1039
1037

T. Bach, C. Körber
FULL PAPER
C7H15NO2Sϩ], 121 (28) [C3H7NO2Sϩ], 104 (100) [C3H6NOSϩ], 62 white solid. Ϫ Rf ϭ 0.23 (CH2Cl2/methanol, 98:2). Ϫ M.p.
(85) [C2H6Sϩ], 57 (62) [C4H9ϩ]. Ϫ C7H15NO2S (177.26): calcd. C
47.43, H 8.53, N 7.90; found C 47.20, H 8.40, N 7.75.
81Ϫ83°C. Ϫ IR (KBr): ν˜ ϭ 1644 cmϪ1 (s, CϭO), 1268 (s,
CϪOϪC), 1166 (s, CϪOϪC), 759 (s, CϪS). Ϫ 1H NMR (200
MHz): δ ϭ 1.48 [s, 9 H, C(CH3)3], 4.07 (d, 2J ϭ 12.25 Hz, 1 H,
CHH), 4.52 (d, 2J ϭ 12.5 Hz, 1 H, CHH), 6.95Ϫ6.98 (m, 2 H,
arom. H), 7.17Ϫ7.29 (m, 3 H, arom. H), 7.35Ϫ7.54 (m, 5 H, arom.
H). Ϫ 13C NMR (50 MHz): δ ϭ 28.3 [C(CH3)3], 57.4 (CH2Ph),
78.9 [C(CH3)3], 127.4 (arom. C), 128.4 (arom. C), 128.6 (arom. C),
128.8 (arom. C), 129.2 (arom. C), 130.4 (arom. C), 132.1 (arom.
C), 133.3 (arom. C), 164.4 (CϭO). Ϫ MS (70 eV); m/z (%): 259 (5)
[C14H13NO2Sϩ], 215 (9) [C13H13NSϩ], 200 (1) [C13H12Sϩ], 91 (100)
[C7H7ϩ] 77 (4) [C6H5ϩ], 57 (41) [C4H9ϩ]. Ϫ C18H21NO2S (315.43):
calcd. C 68.54, H 6.71, N 4.44; found C 68.33, H 6.94, N 4.37.
N-tert-Butyloxycarbonyl Methyl Phenyl Sulfimine (4b): The reac-
tion was carried out as described in typical procedure B starting
from methyl phenyl sulfide[33a] (2b). 195 mg (82%) of 4b was ob-
tained as a white solid. Ϫ Rf ϭ 0.48 (CH2Cl2/methanol, 95:5). Ϫ
M.p. 82Ϫ83°C. Ϫ IR (KBr): ν˜ ϭ 1627 cmϪ1 (s, CϭO), 1281 (s,
CϪOϪC), 1160 (s, CϪOϪC), 748 (s, CϪS). Ϫ 1H NMR (300
MHz): δ ϭ 1.39 [s, 9 H, C(CH3)3], 2.72 (s, 3 H, SCH3), 7.44Ϫ7.48
(m, 3 H, arom. H). 7.67Ϫ7.70 (m, 2 H, arom. H). Ϫ 13C NMR
(75.5 MHz): δ ϭ 28.6 [C(CH3)3], 36.0 (SCH3), 79.1 [C(CH3)3],
126.2 (arom. C), 130.0 (arom. C), 132.2 (arom. C), 137.3 (arom.
C), 164.6 (CϭO). Ϫ MS (70 eV); m/z (%): 239 (1) [Mϩ
ϭ
Procedure for the Nitrene Transfer to Sulfides in the Presence of
Acetyl Acetone. ؊ Typical Procedure C: 1 mmol of BocN3 (143 mg)
and 2.5 mmol of sulfide 2 were dissolved in 0.75 mL of dry CH2Cl2
and the mixture was cooled to 0°C. At this temperature 0.25 mmol
of FeCl2 (34 mg) was added. Upon addition of 0.13 mL of acetyl
acetone (1.3 mmol) the color of the solution turned from brown to
red and nitrogen evolved. After stirring for 5 h at 0°C, the reaction
mixture was poured into 5 mL of water and the aqueous layer was
extracted with CH2Cl2 (5 ϫ 3 mL). The combined organic layers
were washed with water and dried with MgSO4. After filtration,
the solvent was removed in vacuo and the residue was purified by
column chromatography (CH2Cl2/methanol, 100:0 Ǟ 80:20). The
sulfimides 4 were obtained in the yields which are summarized in
Table 4.
C12H17NO2Sϩ], 124 (100) [C7H8S], 77 (14) [C6H5ϩ], 57 (53)
[C4H9ϩ]. Ϫ C12H17NO2S (239.33): calcd. C 60.22, H 7.16, N 5.85;
found C 60.04, H 6.85, N 5.89.
N-tert-Butyloxycarbonyl Isopropyl Methyl Sulfimine (4e): The reac-
tion was carried out as described in typical procedure B starting
from isopropyl methyl sulfide[33a] (2e). 90 mg (40%) of 4e was ob-
tained as a colorless oil. Ϫ Rf ϭ 0.07 (CH2Cl2/methanol, 98:2). Ϫ
IR (film): ν˜ ϭ 1627 cmϪ1 (s, CϭO), 1288, (s, CϪOϪC), 787 (s,
CϪS), 754 (s, CϪS). Ϫ 1H NMR (300 MHz): δ ϭ 1.22 (d, 3J ϭ
6.8 Hz, 3 H, CH3CHCH3), 1.25 (d, 3J ϭ 6.8 Hz, 3 H, CH3CHCH3),
1.35 [s, 9 H, C(CH3)3], 2.42 (s, 3 H, SCH3), 3.07 (sept, 3J ϭ 6.8
Hz, 1 H, CH3CHCH3). Ϫ 13C NMR (75.5 MHz): δ ϭ 15.7
(CH3CHCH3), 16.4 (CH3CHCH3), 26.9 (SCH3), 28.3 [C(CH3)3],
48.7 (CH3CHCH3), 78.3 [C(CH3)3], 165.0 (CϭO). Ϫ MS (70 eV);
m/z (%): 205 (2) [Mϩ ϭ C9H19NO2Sϩ], 90 (26) [C5H10S], 57 (100)
[C4H9ϩ]. Ϫ C9H19NO2S (205.32): calcd. C 52.65, H 9.33, N 6.82;
found C 52.41, H 9.49, N 6.99.
Acknowledgments
This work was supported by the Fonds der Chemischen Industrie
and by the Graduiertenkolleg “Metallorganische Chemie” (scholar-
ship to C. K.).
tert-Butyl N-tert-Butyloxycarbonyl Methyl Sulfimine (4f): The reac-
tion was carried out as described in typical procedure B starting
from tert-butyl methyl sulfide[33a] (2f). 13 mg (6%) of 4f was ob-
tained as a colorless oil. Ϫ Rf ϭ 0.13 (CH2Cl2/methanol, 98:2). Ϫ
[1]
[1a]
Reviews:
S. G. Pyne, Sulfur Rep. 1992, 12, 57Ϫ93. Ϫ
[1c]
Ϫ1
˜
M.p. 103Ϫ104°C. Ϫ IR (KBr): ν ϭ 1642 cm (s, CϭO), 1271 (s,
[1b]
C. R. Johnson, Aldrichim. Acta 1985, 18, 3Ϫ10. Ϫ
M.
CϪOϪC), 1158 (s, CϪOϪC), 831 (s, CϪS), 744 (s, CϪS). Ϫ 1H
NMR (200 MHz): δ ϭ 1.25 [s, 9 H, SC(CH3)3], 1.37 [s, 9 H,
OC(CH3)3], 2.34 (s, 3 H, SCH3). Ϫ 13C NMR (50 MHz): δ ϭ 23.6
[SC(CH3)3], 25.3 (SCH3), 28.3 [OC(CH3)3], 53.9 [SC(CH3)3], 78.2
[OC(CH3)3], 165.5 (CϭO). Ϫ MS (70 eV); m/z (%): 163 (0.1)
R. Barbachyn, C. R. Johnson in Asymmetric Synthesis, vol. 4
(Eds.: J. D. Morrison, J. Schott), Academic Press, New York,
[1d]
1984, pp. 227Ϫ261. Ϫ
M. Haake, Methoden Org. Chem.
(Houben-Weyl), 4th ed. 1985, vol. E 11, pp. 1299Ϫ1320. Ϫ
[1e]
C. R. Johnson in Comprehensive Organic Chemistry, vol. 3
(Eds.: D. H. Barton, W. D. Ollis), Pergamon, New York, 1979,
[1f]
[C6H13NO2Sϩ], 146 (5) [C6H12NOSϩ], 57 (100) [C4H9ϩ].
Ϫ
pp. 223Ϫ232. Ϫ
R. D. Kennewell, J. B. Taylor, Chem. Soc.
Rev. 1975, 4, 189Ϫ209.
C10H21NO2S (219.35): calcd. C 54.75, H 9.65, N 6.38; found C
54.55, H 9.10, N 6.12.
[2]
[2a]
Reviews:
M. Haake, Methoden Org. Chem. (Houben-Weyl),
[2b]
4th ed. 1985, vol. E 11, pp. 887Ϫ910. Ϫ
C. R. Johnson in
Comprehensive Organic Chemistry, vol. 3 (Eds.: D. H. Barton,
W. D. Ollis), Pergamon, New York, 1979, pp. 215Ϫ222. Ϫ
[2c] T. L. Gilchrist, C. J. Moody, Chem. Rev. 1977, 77, 409Ϫ435.
Benzyl N-tert-Butyloxycarbonyl Ethyl Sulfimine (4g): The reaction
was carried out as described in typical procedure B starting from
benzyl ethyl sulfide[33b] (2g). 240 mg (90%) of 4g was obtained as
a colorless oil. Ϫ Rf ϭ 0.20 (CH2Cl2/methanol, 98:2). Ϫ IR (film):
ν˜ ϭ 1615 cmϪ1 (s, CϭO), 1292 (s, CϪOϪC), 1166 (s, CϪOϪC),
[3] [3a]
H. Kwart, A. A. Kahn, J. Am. Chem. Soc. 1967, 89,
[3b]
1950Ϫ1951. Ϫ
D. R. Rayner, D. M. von Schriltz, J. Day, D.
[3c]
J. Cram, J. Am. Chem. Soc. 1968, 90, 2721Ϫ2723. Ϫ
C. R.
Johnson, C. W. Schroeck, J. Am. Chem. Soc. 1968, 90,
6852Ϫ6854. Ϫ [3d] D. J. Cram, J. Day, D. R. Rayner, D. M. von
Schriltz, D. J. Duchamp, D. G. Garwood, J. Am. Chem. Soc.
1970, 92, 7369Ϫ7384. Ϫ [3e] C. R. Johnson, R. A. Kirchhoff, R.
J. Reischer, G. F. Katekar, J. Am. Chem. Soc. 1973, 95,
1
835 (s, CϪS),700 (s, CϪS). Ϫ H NMR (200 MHz): δ ϭ 1.48 [s, 9
3
H, C(CH3)3], 1.30 (t, J ϭ 7.2 Hz, 3 H, CH2CH3), 2.68Ϫ2.88 (m,
2
2
2 H, CH2CH3), 4.03 (d, J ϭ 12.7 Hz, 1 H, CHH), 4.33 (d, J ϭ
12.7 Hz, 1 H, CHH), 7.29Ϫ7.38 (m, 5 H, arom. H). Ϫ 13C NMR
(50 MHz): δ ϭ 7.7 (CH2CH3), 28.2 [C(CH3)3], 37.7 (CH2CH3),
51.3 (CH2Ph), 78.4 [C(CH3)3], 128.8 (arom. C), 129.0 (arom. C),
130.0 (arom. C), 164.8 (CϭO). Ϫ MS (70 eV); m/z (%): 211
(19)[C10H13NO2Sϩ], 91 (100) [C7H7ϩ], 57 (100) [C4H9ϩ], 29 (48)
[C2H5ϩ]. Ϫ C14H21NO2S (219.35): calcd. C 62.89, H 7.92, N 5.24;
found C 62.61, H 7.70, N 5.29.
4287Ϫ4291. Ϫ [3f] C. R. Johnson, C. W. Schroeck, J. Am. Chem.
[3g]
Soc. 1973, 95, 7418Ϫ7423. Ϫ
C. E. Chivers, R. J. W. Crem-
lyn, T. N. Cronjie, R. A. Martin, Aust. J. Chem. 1976, 29,
[3h]
1573Ϫ1582. Ϫ
R. J. W. Cremlyn, T. N. Cronjie, K. Goul-
´
ding, Aust. J. Chem. 1979, 32, 445Ϫ452. Ϫ [3i] S. Juge, G. Meyer,
[3j]
´
F. Ruff, G. Szabo, J.
Tetrahedron 1980, 36, 959Ϫ964. Ϫ
Vaida, I. Kövesdi, A. Kucsman, Tetrahedron 1980, 36,
1631Ϫ1641. Ϫ [3k] R. S. Glass, K. Reineke, M. Shanklin, J. Org.
[3l]
Chem. 1984, 49, 1527Ϫ1533. Ϫ
S. S. Taj, R. Soman, Tetra-
Benzyl N-tert-Butyloxycarbonyl Phenyl Sulfimine (4h): The reaction
was carried out as described in typical procedure B starting from
benzyl phenyl sulfide (2h). 289 mg (92%) of 4h was obtained as a
[3m]
hedron: Asymmetry 1994, 5. 1513Ϫ1518. Ϫ
S. S. Taj, A. C.
Shah, D. Lee, G. Newton, R. Soman, Tetrahedron: Asymmetry
1995, 6. 1731Ϫ1740.
1038
Eur. J. Org. Chem. 1999, 1033Ϫ1039

N-tert-Butyloxycarbonyl-(Boc-)Protected Sulfoximines and Sulfimines
FULL PAPER
J.-C. Hannachi, A. Aubry, A. Collet, Chem. Eur. J. 1997, 3,
[4] [4a]
L. Horner, A. Christmann, Chem. Ber. 1963, 96, 388Ϫ398.
[4b]
Ϫ
P. Svornos, V. Horak, Synthesis 1979, 596Ϫ598.
1691Ϫ1709.
[5]
[6]
[16]
[17]
[16a]
P. W. Heintzelmann, D. Swern, Synthesis 1976, 731Ϫ733.
Sulfoxide imidation:
G. W. Kirby, J. W. M. Mackinnon, R.
[16b]
[6a] F. G. Mann, W. J. Pope, J. Chem. Soc. 1922, 121, 1052Ϫ1055.
P. Sharma, Tetrahedron Lett. 1977, 215Ϫ218. Ϫ
G. W.
[6b]
Ϫ
C. W. Todd, J. H. Fletcher, D. S. Tarbell, J. Am. Chem.
Kirby, H. McGuigan, J. W. M. Mackinnon, D. McLean, R. P.
[6c]
Soc. 1943, 65, 350Ϫ354. Ϫ
A. Kucsman, I. Kapovits, M.
Sharma, J. Chem. Soc., Perkin Trans. 1 1985, 1437Ϫ1442.
Balla, Tetrahedron 1962, 18, 75Ϫ78. Ϫ [6d] K. Tsujihara, N. Fu-
rukawa, K. Oae, S. Oae, Bull. Soc. Chem. Jpn. 1969, 42,
2631Ϫ2635. Ϫ [6e] H. Yoshida, M. Yoshikane, T. Ogata, S. Ino-
Sulfide imidation:
Chem. Soc. Jpn. 1971, 44, 2278 -
W. Ando, N. Ogino, T. Migita, Bull.
[17a]
[17b]
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