Synthesis of β-oxo carbonyl and thiocarbonyl compounds via basic sulfur abstraction

Article abstract of DOI:10.1016/j.tet.2019.130552

Sulfur abstraction from suitable thioesters represents a mild method for the formation of carbon-carbon bonds and the formation of 1,3-dicarbonyl compounds. A study of the scope and limitations of this reaction for the synthesis of these or mixed 1,3-carbonyl/thiocarbonyl compounds by a base promoted sulfur abstraction rearrangement is described. These reactions were typically very clean and the products were obtained in good yield (65–95%) in just 30 min. This method is particularly efficient for the introduction of thiocarbonyl containing groups. Thus, it constitutes a synthetic strategy for the generation of a new carbon-carbon bond and the regioselective preparation of mixed β-dicarbonyl compounds.

Full text of DOI:10.1016/j.tet.2019.130552

Journal Pre-proof
Synthesis of β-oxo carbonyl and thiocarbonyl compounds via basic sulfur abstraction
Saúl Silva, Christopher D. Maycock
PII:
S0040-4020(19)30885-3
https://doi.org/10.1016/j.tet.2019.130552
TET 130552
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 2 August 2019
Revised Date: 16 August 2019
Accepted Date: 21 August 2019
Please cite this article as: Silva Saú, Maycock CD, Synthesis of β-oxo carbonyl and thiocarbonyl
compounds via basic sulfur abstraction, Tetrahedron (2019), doi: https://doi.org/10.1016/
j.tet.2019.130552.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition
of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of
record. This version will undergo additional copyediting, typesetting and review before it is published
in its final form, but we are providing this version to give early visibility of the article. Please note that,
during the production process, errors may be discovered which could affect the content, and all legal
disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier Ltd.

Synthesis of β-oxo carbonyl and thiocarbonyl compounds via basic sulfur abstraction
Saúl Silvaa and Christopher D. Maycocka, b, *
a Instituto de Tecnologia Quım
́
ica e Biológica – António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras,
Portugal
b Departamento de Quım
Portugal
́
ica e Bioquımica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa,
́
Congratulations on this special issue and for services to chemistry and chemists.
Corresponding author e-mail: maycock@itqb.unl.pt
Abstract
Sulfur abstraction from suitable thioesters represents a mild method for the formation
of carbon-carbon bonds and the formation of 1,3-dicarbonyl compounds. A study of the scope
and limitations of this reaction for the synthesis of these or mixed 1,3-carbonyl/thiocarbonyl
compounds by a base promoted sulfur abstraction rearrangement is described. These
reactions were typically very clean and the products were obtained in good yield (65-95%) in
just 30 minutes. This method is particularly efficient for the introduction of thiocarbonyl
containing groups. Thus, it constitutes a synthetic strategy for the generation of a new carbon-
carbon bond and the regioselective preparation of mixed β-dicarbonyl compounds.
Keywords:
desulfurization, β-dicarbonyl compounds, sulfur, rearrangement, synthetic methods, thiocarbonyl derivatives.
1. Introduction
Rearrangement reactions are important transformations in organic chemistry and
particularly useful in synthesis when a new carbon-carbon bond is formed. The sulfur
abstraction in β-oxothioacyl compounds is one example, where two carbons connected
through a sulfur atom become directly connected. The mechanism is exemplified by the
conversion of a β-oxodithiocarbonate (xanthate) into a β-oxothionoester (Scheme 1).
O
O
-H+
S
OEt
-S
S
OEt
R
R
S
S
O
O
S
-S
OEt
R
R
R
OEt
S
S
+H+
O
OH
S
OEt
R
OEt
Scheme 1. Mechanism of sulfur abstraction for a 2-oxodithiocarbonate (xanthate).
This rearrangement was first reported by Lightner and Djerassi1 in 1963 with the
conversion of a steroid β-oxoxanthate into a β-oxothionoester under basic conditions. Later,
Eschenmoser2 described the use of a tertiary phosphine as an alternative reagent, acting as a
thiophile. This method has been extensively used with β-oxothioimidates and is known as the
Eschenmoser sulfide contraction.3 To the best of our knowledge, apart from the Eschenmoser
reaction, this rearrangement has been little used despite its synthetic potential. Some
examples described in the literature4 are summarized in Scheme 2.
1

S
R
S
OAlk
O
OH
S
base
Ref 1, 4a-b
Ref 4c
S
R
R
OAlk
R
S
OEt
SAlk
NaH or K2CO3
R1
R1
AlkylHal
OEt
R2
R2
R1=CO2Et, COMe or CN
R2=CO2Et or Ph
Y
Alk
X
XH
Y
PR3
S
Ref 2-3
Ref 4d
R
R
Alk
R
R
X,Y=O or NR
R1
O
O
LiNR2 EtO2C
R1
EtO2C
S
R
R
R1= Ph, t or nBu
O
R
R
O
P(OPh)2
Ref 4e-f
NaH, PPh3
O
N
S
N
(PhO)2POCl
O
O
CO2R
CO2R
Br-
R
S+
Ref 4g-i
Ref 4j
∆, Py
O
O
R
S
Ar
R
Ar
S
O
S
OH
R
O
MeO
BBr3
R
R
X
Y
S
O
OH
X
NaH
This work
R
R
Y
X=O or S
Y= Alkyl, Aryl,
OR, NR2, SR
R
R
Scheme 2. Selected examples of sulfur abstraction reactions.
In the present work we have explored the potential of this reaction for the
introduction of different acyl groups via sulfur abstraction. A recent synthesis by the authors
required a 3-keto ester as an intermediate. The requirement of a thioester analogue
stimulated this work since a systematic study has not been reported. We opted to use a base
promoted method since the use of a phosphine is not atom efficient and normally produces
2

significant amounts of by-products. This rearrangement constitutes
a clean and
environmentally benign method for the introduction of different carbonyl and thiocarbonyl
containing groups.
2. Results and Discussion
β-Ketoxanthates or α-xanthyl ketones can be readily prepared by reacting the
respective α-haloketones with the corresponding xanthate salt. Using the commercially
available ethyl potassium xanthate a series of cyclic β-oxo ethyl xanthates was prepared and
reacted with sodium hydride in order to promote the rearrangement (Scheme 3). The
subsequent sulfur extrusion reaction was very clean and fast when using good quality sodium
hydride. Initially two simple substrates (1a and 1b) were used and the respective β-
oxothionoesters 2a and 2c were obtained in moderate yields. Other substituted
cyclohexanones were also used and the respective thionoesters 2c-f were also obtained in
good yields. A highly functionalized optically active thionoester 2g was also prepared in good
yield, demonstrating the compatibility of this transformation with different functional groups.
6-(Ethylxanthate)-2-cyclohexenone 1h was prepared from 6-chloro-2-cyclohexenone.
Although Michael addition of the xanthate occurs, we found that chlorine substitution is also
possible when using two equivalents of xanthate. Upon using a sodium bicarbonate solution in
the work-up, instead of water, the xanthate group added to the enone eliminates and 1h is
obtained. In the rearrangement of 1h the expected product 2h is obtained, however a
secondary product 2h’ is also produced. The product 2h’, containing two cyclohexane rings
fused by a cyclobutane, is produced by Michael addition of the enolate formed. In an attempt
to avoid 2h’ formation the reaction was carried at a lower temperature (-20 °C), however the
opposite effect was observed and the yield of 2h’ increased to 40%. Although it was not
investigated, performing the reaction at an even lower temperature could lead to the exclusive
formation of 2h’.
3

O
OH
S
NaH
S
OEt
R1
R1
OEt
THF, 0ºC
30 min
R2
S
R2
1
2
OH
OH
S
OH
S
S
OEt
OEt
OEt
65%
79%
81%
2b
2c
2a
OH
S
OH
S
OEt
93%
OEt
90%
Ph
2e
2d
OH
S
OH
S
OEt
N
OEt
92%
OTBS 94%
2g
2f
OH
S
OH
O
S
OEt
OEt
75%
S
S
2h
OEt
11%
2h'
Scheme 3. Cyclic β-oxo thionoesters synthesis via sulfur abstraction of the respective β-oxo xanthates.
As for β-oxoxanthates, β-oxothioacetates were easily prepared by chloride substitution
using commercially available potassium thioacetate. A series of β-oxo thioacetates was also
prepared and submitted to the same conditions (Scheme 4). Two linear substrates were tested
and the respective β-diketones (2i and 2j) were obtained in good yield. Thioacetate 1k was
prepared in the same way as 1h. Upon reaction with sodium hydride 2k was obtained in good
yield and the Michael addition that produced 2h’ was not observed. 3-Thioacetate 4-
tertbutylcyclohexanone 1l was tested for comparison with the structurally similar ethyl
xanthate 1d and 2l was obtained in a similar yield as 2d. 2-Thioacetate cyclooctanone 1m and
cyclododecanone 1n were prepared by chlorine substitution, however the reaction had to be
carried at 70 °C for 70 hours. For 2-chloro substituted cycloketones having a larger ring,
chloride displacement proved to be more difficult and substitution with ethyl xanthate was not
possible. The respective β-diketones (2m and 2n) were, however, obtained in good yields.
4

O
OH
O
NaH
S
R1
R1
O
THF, 0ºC
30 min
R2
O
R2
1
2
O
O
OH
88%
90%
2i
2j
OH
O
O
O
84%
O
91%
2k
OH
2l
O
O
95%
95%
2m
2n
Scheme 4. β-Diketone synthesis via sulfur abstraction from the respective β-oxo thioacetates.
Tetralone was used as a model to study the reaction with different carbonyl and
thiocarbonyl containing groups attached to the sulfur atom (Table 1). Compounds 1o and 1p
were prepared by halogen substitution using the corresponding salt. Reaction of
dithiocarbamate 1o produced thioamide 2o in good yield, however the reaction had to be
carried at 60 °C and hence the solvent was changed to DMF. The sodium enolate of 1o is
formed at lower temperatures, as can be observed by hydrogen production, however the
sulfur abstraction only occured when the temperature was raised to 60 °C. Dithioester 2p was
also obtained in good yield.
5

Table 1. Basic rearrangement of different 2-S-carbonyl and thiocarbonyl tetralone derivatives.
O
O
X
NaH
S
Y
Y
THF, 0 ºC
30 min
X
1
2
Entry
Substrate 1
Product 2
Yield
1
91%a
2
85%
71%
21%
3
4
5
100%b
O
S
S
65%
O
1s
6

OH
S
19%
78%
2s'
6
OH
OH
O
S
S
10%
2t'
O
7
8
100%
70%c
2u
SMe
2v
SMe
O
9
66%c
2w
a Reaction was carried in DMF at 60 °C. b Reaction was carried in DMF at 80 °C. c After 30 min, MeI was added.
Compounds 1q-t were obtained via the thiocarbonyl oxidation of compounds 1f, 1o
and 1p. Reaction of monothiocarbonate 1q afforded ester 2q in moderate yield and a
secondary product 2q’ was also formed. The trithiolane 2q’ was probably formed by the
reaction of thioketone 3 with sulfur released during the rearrangement (Scheme 5).5 Two
diastereoisomers of 2q’ are possible but only one was observed. Basic rearrangement of
monothiocarbamate 1r gave 2r in quantitative yield, as for 1o the reaction only occurred at a
higher temperature (80 °C). Instead of sulfur abstraction the carbamate group migrated from
the sulfur to the oxygen, and further dimerization resulted in 2r. Oxidation of trithiocarbonate
1p using permanganate resulted in dithiocarbonate 1s while using m-CPBA gave sulfine 1t.
Although the reaction of 1s produced the expected product 2s, a secondary product 2s’ was
7

also formed. The formation of 2s’ could be due to sulfur and CO elimination or direct
elimination of carbonyl sulfide, and further aromatization, to form 2s’, is possible in the
presence of sulfur. During the rearrangement of 1t both sulfur abstraction and oxygen
migration occurred resulting in the formation of 2t as well as the aromatic secondary product
2t’.
O
OEt
- CO
- EtO-
O
O-
S
S
2q'
S
3
Scheme 5. Proposed mechanism for the formation of trithiolane 2q’.
Compounds 1q-s were less suitable for the rearrangement compared to the respective
thiocarbonyl analogues 1f, 1o and 1p. Their basic rearrangement resulted in the formation of
secondary products (2s’ and 2q’) or sulfur abstraction did not occur at all, as in the case of 1r.
In the proposed mechanism (Scheme 1) an episulfide intermediate needs to be formed for the
sulfur abstraction to occur; however in the case of carbonyl derivatives an alkoxide is formed
instead of a thiolate. Thus, this episulfide intermediate is probably less stable for carbonyl
derivatives, explaining the lower efficiency of the sulfur abstraction.
Considering the good results of thioacetates 1i-n rearrangement, monothiobenzoate
1u and dithioesters 2v and 2w were prepared via the substitution of 2-bromotetralone with
the corresponding salt and then submitted to the normal basic conditions. Reaction of 1u
resulted in the expected product 2u in quantitative yield. Rearrangement of dithioesters 1v
and 1w produced the expected thioketones, however the products were unstable and
degradation was observed upon air exposure or chromatographic purification. In order to
easily isolate the products, they were methylated with iodomethane using a one-pot
procedure and 2v and 2w were obtained as a mixture of two diastereoisomers. Other
methylation (O and C) products were observed in the NMR spectra of the crude product and
may explain the lower yields of 2v and 2w.
A dithiophosphate derivative 1x (Scheme 6) was also prepared and submitted to basic
conditions in order to determine if sulfur abstraction was also possible in a phosphorous
analogue. However only the migration of phosphate from the sulfur to the carbonyl oxygen
atom occurred and 2x was obtained. In this case dimerisation via the formation of a disulfide
bond was not observed.
S
OEt
P
O
O
OEt
SH
S
OEt
OEt
NaH
P
S
THF, 0ºC
2x (95%)
1x
Scheme 6. Basic rearrangement of the 2-diethyldithiophosphate ester of tetralone 1x.
8

3. Conclusion
Sulfur abstraction from α-thiocarbonyl ketones under basic conditions is a useful
synthetic methodology for the preparation of β-dicarbonyl compounds through the generation
of a new carbon-carbon bond. Although synthetic applications described in the literature are
mostly restricted to the Eschenmoser method, a broader range of substrates has been
demonstrated. It is normally a very clean reaction and the products are obtained with good
yields. It is particularly useful for the introduction of a thiocarbonyl containing group:
thioketone, thionoester, thioamide and dithioester. In addition to its potential for new
synthetic applications, the β-dicarbonyl compounds produced are useful as ligands in metal
complexes especially when containing a thiocarbonyl group. The generation of acid derivatives
such as esters, amides and thioesters, using this method, seems to be problematic compared
to the respective thiocarbonyl analogues.
4. Experimental
4.1.General
All chemicals used were of reagent grade. All solvents were dried by established
methods.6 Flash chromatography was performed on Kieselgel 60, particle size 0.032–
0.063 mm. Analytical TLC: Aluminium-backed silica gel Merck 60 F254. Infrared (IR) spectra were
obtained using commercial ATR-FTIR spectrophotometer and are in cm−1. Specific rotations
were measured using an automatic polarimeter and are reported as follows: [∝]ꢁꢀ (c=
g/100mL; solvent). Melting points were determined with a capillary apparatus and are
uncorrected. HRMS was recorded on a commercial apparatus (ESI-TOF). NMR spectra were
obtained with a commercial 400 MHz (1H NMR) instrument, 101 MHz (13C NMR) and 162 MHz
(31P NMR) using CDCl3 as solvent. Chemical shifts are reported in parts per million relative to
TMS (1H and 13C) or phosphoric acid (31P) and coupling constants in hertz. The chemical shift
assignments of all compounds were carried out with the help of 2D NMR experiments such as
COSY, HMQC and HMBC.
4.2.General procedure for the synthesis of 2-oxo-S-carbonyl or thiocarbonyl compounds
1
To a stirred solution of 2-chloroketone (6.4mmol) in dry acetone (13mL) under argon
atmosphere was added potassium ethyl xanthate, potassium thioacetate or other salt (1.2eq.).
After reaction completion (followed by TLC, 2-8h), water was added (20mL) and extracted with
DCM (3X10mL). The combined organic layers were dried with MgSO4 and evaporated to
dryness. Products were purified by chromatography (flash column or preparative TLC).
4.2.1. Ethyl [(2-oxocyclopentyl)sulfanyl]methanethioate 1b
A described procedure7 for the preparation of the compound was followed.
3
1H NMR δ: 4.15 (2H, q, J=7.1, CH2 Et); 4.15 (1H, t, J=9.4, J=1.6, H-1); 2.66-2.59 (1H, m,
2
2
H-5); 2.45 (1H, dm, J=18.8, H-3); 2.30 (1H, dt, J=18.8, J3,4=9.5, H-3); 2.18-2.11 (1H, m, H-4);
2.08-1.89 (2H, m, H-4, H-5); 1.42 (3H, t, 3J=7.1, CH3 Et). 13C NMR δ: 212.5, 212.4 (C-2, C=S); 70.6
(CH2 Et); 55.0 (C-1)); 37.0 (C-3); 30.2 (C-5); 20.7 (C-4); 13.7 (CH3 Et). FTIR (neat): 1743 (C=O st.),
1209 (C-O-C st.), 1039 (C=S st.).
9

4.2.2. Ethyl [(3-methyl-2-oxocyclohexyl)sulfanyl]methanethioate 1c
By means of the general procedure, 127 mg (55% yield) of product were obtained as a
colorless oil after purification by preparative TLC (eluted with 4:6 Hex:DCM).
1H NMR δ: 4.65-4.55 (2.8H, m, CH2 Et, H-1); 4.54 (0.2H, t, J=5.2, H-1’); 2.90-2.81 (0.2H,
m, H-3’); 2.67-2.54 (1.6H, m, H-3, H-6); 2.36-2.00 (1.4H, m, H-4, H-4’, H-6’); 1.99-1.70 (2.8H, m,
3
H-5, H-5’, H-6); 1.56-1.43 (1H, m, H-4, H-4’); 1.40 (3H, t, J=7.1, CH3 Et), 1.11 (0.6H, d, J=6.7,
Me’), 1.09 (2.4H, d, J=6.5, Me’). 13C NMR δ: 213.8 (211.2) (C=S); 206.5 (208.4) (C-2); 70.1 (70.4)
(CH2 Et); 60.6 (56.0) (C-1); 46.0 (42.8) (C-3); 36.7 (35.5) (C-4); 35.2 (33.5) (C-6); 25.8 (21.5) (C-5),
14.6 (15.1) (Me); 13.8 (13.6) (CH3 Et). FTIR (neat): 1712 (C=O st.), 1209 (C-O-C st.), 1046 (C=S
st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C10H16NaO2S2 255.0484; Found 255.0480.
4.2.3. Ethyl [(5-tert-butyl-2-oxocyclohexyl)sulfanyl]methanethioate 1d
By means of the general procedure, 1.3g (74% yield) of product were obtained as a
colorless oil (74% yield) after purification by flash column chromatography (eluted with 95:5
Hex:EtOAc).
1H NMR δ: 4.68-4.43 (3H, m, H-1, CH2 Et); 2.78-1.96 (4H, m); 1.80-1.48 (3H, m); 1.41
(3H, t, 3J=7.2, CH3 Et); 0.94 (0.90) (9H, s, tBu). 13C NMR δ: 213.5 (210.5) (C=S); 205.2 (207.1) (C-
2); 70.2 (70.5) (CH2 Et); 60.0 (55.1) (C-1)); 47.7 (43.1) (C-5); 41.3 (38.2) (CH2); 35.7 (33.2) (CH2);
32.7 (32.4) (Cq tBu); 28.3 (27.42) (CH2); 27.6 (27.39) (3xCH3 tBu); 13.8 (13.6) (CH3 Et). FTIR
(neat): 1717 (C=O st.), 1216 (C-O-C st.), 1052 (C=S st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
C13H22NaO2S2 297.0953; Found 297.0949.
4.2.4. Ethyl [(2-oxo-5-phenylcyclohexyl)sulfanyl]methanethioate 1e
By means of the general procedure, 221 mg (75% yield) of product were obtained as a
colorless oil after purification by flash column chromatography (eluted with 95:5 Hex:EtOAc).
1H NMR δ: 7.36-7.23 (5H, m, Ar); 4.79 (0.85H, dd, J=13.4, J=5.7, H-1); 4.67-4.58 (2H, m,
CH2 Et); 4.54 (0.15H, dt, J=4.7, J=1.6, H-1); 3.33-3.17 (1H, m, H-5); 2.93-1.97 (6H, m, H-3, H-4,
3
H-6); 1.43 (1.40) (3H, t, J=7.1, CH3 Et). 13C NMR δ: 213.3 (210.1) (C=S); 204.2 (205.7) (C-2);
143.3 (143.2) (Cq Ar); 128.8 (Ar(m)); 127.0 (126.9) (Ar(p)); 126.7 (126.8) (Ar(o)); 70.4 (70.6) (CH2
Et); 59.7 (55.2) (C-1); 43.7 (38.8) (C-5); 41.5, 41.2, 34.4 (39.2, 38.4, 33.7) (C-3, C-4, C-6); 13.8
(13.6) (CH3 Et). FTIR (neat): 1716 (C=O st.), 1220 (C-O-C st.), 1049 (C=S st.). HRMS (ESI-TOF)
m/z: [M + Na]+ Calcd for C15H18NaO2S2 317.0640; Found 317.0644.
4.2.5. Ethyl
{[(1S,5S,6R)-5-[(tert-butyldimethylsilyl)oxy]-2-oxo-7-(prop-2-en-1-yl)-7-
azabicyclo[4.1.0]heptan-3-yl]sulfanyl}methanethioate 1g
By means of the general procedure, 696 mg (84% yield) of product were obtained as a
colorless oil after purification by flash column chromatography (eluted with 95:5 Hex:EtOAc).
1H NMR δ: 5.94-5.82 (1H, m, H-2’); 5.39-5.32 (1H, m, H-3’); 5.18-5.13 (1H, m, H-3’);
4.75 (0.3H, dd, J3,4=6.8, J3,4=5.0, H-3 II); 4.71-4.60 (2H, m, CH2 Et); 4.27-4.19 (1.7H, m, H-3 I, H-
5); 3.32 (0.7H, ddt, 2J=14.4, J1’,2’=5.3, J1’,3’=1.4, H-1’ I); 3.19 (0.3H, ddt, 2J=14.4, J1’,2’=5.4, J1’,3’=1.4,
2
2
H-1’ II); 2.94 (0.3H, ddt, J=14.4, J1’,2’=5.3, J1’,3’=1.4, H-1’ II); 2.81 (0.7H, ddt, J=14.4, J1’,2’=5.3,
J1’,3’=1.4, H-1’ I); 2.63 (0.3H, ddd, 2J=14.0, J4,5=8.7, J4,3=6.9, H-4 II); 2.36-2.17 (2.7H, m, H-1, H-4 I,
2
2
H-6); 2.11 (0.7H, dtd, J=12.1, J4,5=J4,3=6.0, J4,6=0.6, H-4 I); 1.94 (0.3H, dtd, J=13.9, J4,5=J4,3=5.3,
3
t
J4,6=0.6, H-4 II); 1.42 (3H, t, J=7.1, CH3 Et); 0.92 (9H, s, Bu TBDMS); 0.13 (2.1H, Me TBDMS I);
0.12 (2.1H, Me TBDMS I); 0.11 (0.9H, Me TBDMS II); 0.09 (0.9H, Me TBDMS II). 13C NMR δ:
10

213.4 (211.2) (C=S); 199.1 (201.4) (C-2); 133.8 (133.9) (C-2’); 117.05 (117.14) (C-3’); 70.8 (70.5)
(CH2 Et); 67.6 (65.5) (C-5); 61.81 (61.75) (C-1’); 53.6 (51.4) (C-3); 46.8, 45.5 (49.1, 46.1) (C-1, C-
t
t
6); 32.5 (36.0) (C-4); 25.7 (25.8) (3x CH3 Bu); 18.08 (18.11) (Cq Bu); 13.8 (13.7) (CH3 Et); -4.60, -
4.66, -4.71 (Me TBDMS). FTIR(NEAT): 1716 (C=O st.); 1219 (C-O-C st.); 1096 (Si-O st.); 1049 (C=S
ꢄ
st.); 837 (Si-O-C bend.); 777. [∝]ꢂꢀꢃ ꢅ= -125 (c=1.0; DCM). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C18H31NNaO3S2Si 424.1407; Found 424.1414.
4.2.6. Ethyl [(2-oxocyclohex-3-en-1-yl)sulfanyl]methanethioate 1h
The general procedure was followed except that 2eq. of potassium ethyl xanthate
were used instead of 1.2. After purification by flash column chromatography (eluted with 9:1
Hex:EtOAc), 158 mg (48% yield) of product were obtained as a colorless oil.
1H NMR δ: 7.02 (1H, dt, J4,3=9.1, J4,5=4.0, H-4); 6.12 (1H, d, J3,4=10.1, H-4); 4.72-4.61 (3H,
m, CH2 Et, H-1); 2.62-2.45 (3H, m, H-5, H-6); 2.29-2.18 (1H, m, H-6); 1.42 (3H, t, 3J=7.1, CH3 Et).
13C NMR δ: 211.9 (C=S); 193.4 (C-2); 150.4 (C-4); 129.1 (C-3); 70.4 (CH2 Et); 56.1 (C-1); 29.7 (C-
6); 25.9 (C-5); 13.8 (CH3 Et). FTIR (neat): 1679 (C=O st.), 1210 (C-O-C st.), 1042 (C=S st.). HRMS
(ESI-TOF) m/z: [M + Na]+ Calcd for C9H12NaO2S2 239.0171; Found 239.0176.
4.2.7. 2-(Acetylsulfanyl)-1-phenylpropan-1-one 1i8
By means of the general procedure, 129 mg (62% yield) of product were obtained as a
colorless oil after purification by preparative TLC (eluted with 9:1 Hex:EtOAc).
4.2.8. 2-(Acetylsulfanyl)-1-phenylethan-1-one 1j8-9
By means of the general procedure, 604 mg (96% yield) of product were obtained as a
white solid after purification by flash column chromatography (eluted with 9:1 Hex:EtOAc).
4.2.9. 6-(Acetylsulfanyl)cyclohex-2-en-1-one 1k
By means of the same procedure as for 1h (but with KSAc), 107 mg (53% yield) of the
pure product were obtained as a colorless oil after purification by flash column
chromatography (eluted with 95:5 Hex:EtOAc).
1H NMR δ: 7.02 (1H, dddd, J3,2=10.0, J3,4=4.7, J3,4=3.5, J3,5=0.9, H-3); 6.11 (1H, ddd,
J2,3=10.1, J2,4=2.4, J2,4=1.6, H-2); 4.35 (1H, dd, J6,5=11.7, J6,5=4.7, H-6); 2.61-2.44 (2H, m, H-4);
2
2.40-2.29 (1H, m, H-5); 2.39 (3H, s, CH3 Ac); 2.15 (1H, dddd, J=13.3, J5,6=11.7, J5,4=9.3, J5,4=5.3,
H-5). 13C NMR δ: 194.14, 194.12 (C-1, C=O Ac); 150.5 (C-3); 129.2 (C-2); 49.7 (C-6); 30.6 (CH3
Ac); 30.2 (C-5); 25.7 (C-4). FTIR (neat): 1674 (C=O st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
C8H10NaO2S 193.0294; Found 193.0293.
4.2.10. 2-(Acetylsulfanyl)-4-tert-butylcyclohexan-1-one 1l
By means of the general procedure, 1.3g (88% yield) of product were obtained as a
white solid after purification by flash column chromatography (eluted with 95:5 Hex:EtOAc).
2
1H NMR δ: 4.31 (1H, dd, J2,3=13.3, J2,3=5.8, H-2); 2.59 (1H, dt, J=14.0, J6,5=3.5, H-6);
2.39-2.32 (1H, m, H-3); 2.36 (3H, s, CH3 Ac); 2.15 (1H, ddq, 2J=12.7, J5,6=6.2, J5,4=J5,6= J5,3=3.1, H-
2
5); 1.74 (1H, tt, J4,5=J4,3=12.1, J4,5=J4,3=2.8, H-4); 1.56 (1H, q, J=J3,4=J3,2=12.4, H-3); 1.50 (1H, qd,
t
2J=J5,4=J5,6=12.7, J5,6=4.8, H-5); 0.92 (9H, s, Bu). 13C NMR δ: 205.5 (207.6) (C-1); 194.6 (192.5)
(C=O Ac); 53.4 (49.6) (C-2); 47.5 (43.4) (C-4); 41.2 (38.7) (C-6); 36.2 (33.6) (C-3); 32.6 (32.4) (Cq
t
tBu); 30.6 (30.5) (CH3 Ac); 28.1 (26.7) (C-5); 27.6 (27.4) (3XCH3 Bu). FTIR (neat): 1721 (C=O st.
11

ketone), 1686 (C=O st. thioacetate). M.p.=47-49°C. Anal. Calcd for C12H20O2S: C 63.12; H 8.83; S
14.04. Found: C 62.85; H 8.53; S 13.90.
4.2.11. 2-(Acetylsulfanyl)cyclooctan-1-one 1m
The general procedure was followed except that reaction temperature was 70°C (in a
pressure tube), 2.0 eq. of potassium thioacetate were used and the reaction time was 70
hours. After purification by flash column chromatography (eluted with 95:5 Hex:EtOAc),
433mg (70% yield) of product were obtained as a colorless oil.
1H NMR δ: 4.50 (1H, dd, J2,3=10.9, J2,3=3.7, H-2); 2.77 (1H, ddd, 2J=14.2, J8,7=8.1, J8,7=3.2,
2
H-8); 2.41 (1H, ddd, J=14.1, J8,7=10.8, J8,7=3.2, H-8); 2.31 (3H, s, CH3 Ac); 2.17-2.07 (2H, m);
1.89-1.48 (7H, m); 1.19-1.09 (1H, m). 13C NMR δ: 213.2 (C-1); 195.2 (C=O Ac); 51.3 (C-2); 42.2
(C-8); 30.1 (CH3 Ac); 32.2, 27.6, 25.1, 24.8, 24.3 (5XCH2). FTIR (neat): 1708 (C=O st. ketone),
1686 (C=O st. thioacetate). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C10H16NaO2S 223.0763;
Found 223.0761.
4.2.12. 2-(Acetylsulfanyl)cyclododecan-1-one 1n
By means of the same procedure as for 1m, 145 mg (57% yield) of the pure product
were obtained as a white solid after purification by flash column chromatography (eluted with
98:2 Hex:EtOAc).
2
1H NMR δ: 4.55 (1H, dd, J2,3=9.7, J2,3=3.6, H-2); 2.81 (1H, ddd, J=15.7, J12,11=8.5,
2
J12,11=3.4, H-12); 2.35 (1H, ddd, J=15.6, J12,11=9.0, J12,11=3.6, H-12); 2.35 (3H, s, CH3 Ac); 2.09-
2.00 (1H, m, H-3); 1.85-1.66 (3H, m); 1.45-1.17 (14H, m). 13C NMR δ: 207.5 (C-1); 194.5 (C=O
Ac); 50.0 (C-2); 38.5 (C-12); 30.3 (CH3 Ac); 29.2 (C-3); 24.9, 24.8, 24.6, 24.3, 24.2, 23.0, 22.4,
22.2 (8XCH2). FTIR (neat): 1694 (C=O st.). M.p.=65-66°C. Anal. Calcd for C14H24O2S: C 65.58; H
9.44; S 12.50. Found: C 65.50; H 9.53; S 12.48.
4.2.13. N,N-Dimethyl-1-[(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]methanethioamide 1o
By means of the general procedure (using sodium dimethyl-dithiocarbamate hydrate),
1.3g (91% yield) of product were obtained as a white solid after purification by flash column
chromatography (eluted with 1:2 Hex:DCM).
1H NMR δ: 8.07 (1H, dd, J8,7=7.9, J8,6=1.0, H-8); 7.50 (1H, td, J6,5=J6,7=7.5, J6,8=1.3, H-6);
7.33 (1H, t, J7,6=J7,8=7.6, H-7); 7.27 (1H, d, J5,6=7.6, H-5); 5.37 (1H, dd, J2,3=12.6, J2,3=4.6, H-2);
2
3.58 (3H, s, Me); 3.44 (3H, s, Me); 3.28 (1H, ddd, J=16.9, J4,3=11.8, J4,3=4.5, H-4); 3.06 (1H, dt,
2
2
2J=16.9, J4,3=4.0, H-4); 2.69 (1H, dq, J=12.9, J3,4=J3,2=4.3, H-3); 2.32 (1H, qd, J= J3,4=J3,2=12.4,
J3,4=4.3, H-3). 13C NMR δ: 195.3, 193.5 (C-1, C=S); 143.7 (C-4a); 133.8 (C-6); 132.2 (C-8a); 128.8
(C-5); 127.9 (C-8); 126.8 (C-7); 60.0 (C-2); 45.9, 41.7 (2xMe); 31.5 (C-3); 29.7 (C-4). FTIR (neat):
1682 (C=O st.); 1497, 1375, 981 (N-C-S); 1145 (C=S st.); 741 (Ar C-H bend. o.o.p.). M.p.=149°C.
Anal. Calcd for C13H15NOS2: C 58.84; H 5.70; N 5.28; S 24.16. Found: C 59.09; H 5.98; N 5.50; S
23.90.
4.2.14. 2-{[(tert-Butylsulfanyl)methanethioyl]sulfanyl}-1,2,3,4-tetrahydronaphthalen-1-
one 1p
A described procedure10 for the preparation of the compound was followed.
12

1H NMR δ: 8.05 (1H, d, J8,7=7.8, H-8); 7.51 (1H, t, J6,5=J6,7=7.5, H-6); 7.33 (1H, t,
J7,6=J7,8=7.6, H-7); 7.26 (1H, d, J5,6=7.6, H-5); 5.25 (1H, dd, J2,3=11.8, J2,3=4.5, H-2); 3.20 (1H, ddd,
2
2
2J=16.9, J4,3=10.9, J4,3=4.4, H-4); 3.07 (1H, dt, J=16.9, J4,3=4.4, H-4); 2.60 (1H, dq, J=13.3,
J3,4=J3,2=4.4, H-3); 2.30 (1H, qd, J=J3,4=J3,2=11.9, J3,4=4.4, H-3); 1.65 (9H, s, Bu). 13C NMR δ:
2
t
221.4 (C=S); 193.1 (C-1); 143.6 (C-4a); 134.0 (C-6); 132.1 (C-8a); 128.8 (C-5); 128.0 (C-8); 126.9
t
t
(C-7); 56.6 (C-2); 54.8 (Cq Bu); 30.2 (C-3); 29.4 (3xCH3 Bu); 29.2 (C-4). FTIR (neat): 1683 (C=O
st.); 1065 (C=S st.); 804; 794; 740 (Ar C-H bend. o.o.p.). M.p.=95-96°C (lit. 100-101°C).
4.2.15. Ethyl [(1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl)sulfanyl]formate 1q
To a solution of 1f (1g, 3.8 mmol) in DCM (15mL) was added m-CPBA (77%, 1.7g, 2eq.)
at 0°C and the mixture was stirred for 30 min at room temperature. Afterward 20 mL of
NaHCO3 aqueous saturated solution were added and extracted with DCM (3x10mL). The
combined organic layers were dried with MgSO4 and evaporated to dryness. After purification
by flash column chromatography (eluted with 95:5 Hex:EtOAc), 218 mg (23%) of pure product
were obtained as a yellowish white solid.
1H NMR δ: 8.06 (1H, d, J8,7=7.9, H-8); 7.50 (1H, t, J6,5=J6,7=7.5, H-6); 7.33 (1H, t,
J7,6=J7,8=7.6, H-7); 7.26 (1H, d, J5,6=7.4, H-5); 4.38 (1H, dd, J2,3=11.9, J2,3=4.5, H-2); 4.34-4.27 (2H,
2
2
m, CH2 Et); 3.17 (1H, ddd, J=16.9, J4,3=10.8, J4,3=4.5, H-4); 3.08 (1H, dt, J=16.9, J4,3=4.5, H-4);
2.60 (1H, dq, 2J=13.3, J3,4=J3,2=4.5, H-3); 2.37 (1H, qd, 2J= J3,4=J3,2=12.0, J3,4=4.6, H-3); 1.32 (3H, t,
2J=7.1; CH2 Et). 13C NMR δ: 193.1 (C-1); 169.7 (C=O thiocarbonate); 143.4 (C-4a); 133.9 (C-6);
131.8 (C-8a); 128.7 (C-5); 128.1 (C-8); 127.0 (C-7); 64.0 (CH2 Et); 52.7 (C-2); 31.1 (C-3); 29.1 (C-
4); 14.3 (CH3 Et). FTIR (neat): 1698 (C=O st.); 1131 (C-O-C st.); 738 (Ar C-H bend. o.o.p.).
M.p.=53°C. Anal. Calcd for C13H14O3S: C 62.38; H 5.64; S 12.81. Found: C 62.60; H 5.85; S 12.60.
4.2.16. N,N-Dimethyl-1-[(1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl)sulfanyl]formamide
1r
A described procedure for the oxidation of dithiocarbamates was used with some
modifications.11 To a solution of 1o (950 mg, 3.6 mmol), benzoic acid (1 eq., 440 mg) and
benzyltriethylammonium chloride (10 mol%, 83 mg) in DCM (36 mL) was added a solution of
KMnO4 (3 eq., 1.7 g) in water (72 mL) and the reaction mixture was vigorously stirred for 5
hours. Afterward solid sodium metabisulfite was added until the reaction mixture color turned
white which was then diluted with NaHCO3 aqueous saturated solution (50 mL) and extracted
with DCM (3X50 mL). The combined organic layers were dried with MgSO4 and evaporated to
dryness. After purification by flash column chromatography (eluted with 95:5 DCM:EtOAc),
406 mg (45%) of pure product were obtained as a yellowish white solid.
1H NMR δ: 8.06 (1H, d, J8,7=7.9, H-8); 7.48 (1H, t, J6,5=J6,7=7.5, H-6); 7.32 (1H, t,
J7,6=J7,8=7.6, H-7); 7.25 (1H, d, J5,6=7.7, H-5); 4.54 (1H, dd, J2,3=11.8, J2,3=4.5, H-2); 3.17 (1H, ddd,
2J=16.4, J4,3=11.3, J4,3=4.7, H-4); 3.09-3.03 (1H, m, H-4); 3.04 (6H, s, 2xMe); 2.55 (1H, dq,
2
2J=13.2, J3,4=J3,2=4.4, H-3); 2.35 (1H, qd, J=J3,4=J3,2=11.9, J3,4=4.4, H-3). 13C NMR δ: 194.2 (C-1);
166.6 (C=O monothiocarbamate); 143.6 (C-4a); 133.7 (C-6); 132.1 (C-8a); 128.7 (C-5); 128.0 (C-
8); 126.8 (C-7); 52.4 (C-2); 36.8 (2xMe); 31.6 (C-3); 29.3 (C-4). FTIR (neat): 1685 (C=O st.
ketone); 1648 (C=O st. monothiocarbamate); 1365; 1100; 743 (Ar C-H bend. o.o.p.). M.p.=95-
96°C. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C13H16NO2S 250.0896; Found 250.0891.
4.2.17. 2-{[(tert-Butylsulfanyl)carbonyl]sulfanyl}-1,2,3,4-tetrahydronaphthalen-1-one 1s
13

By means of the same procedure as for 1r except the reaction time was 30 min, 947
mg (93% yield) of the pure product were obtained as a colorless oil after purification by flash
column chromatography (eluted with 2:1 Hex:DCM).
1H NMR δ: 8.04 (1H, d, J8,7=7.8, H-8); 7.49 (1H, td, J6,5=J6,7=7.6, J6,8=0.9, H-6); 7.32 (1H, t,
J7,6=J7,8=7.6, H-7); 7.25 (1H, d, J5,6=7.7, H-5); 4.59 (1H, dd, J2,3=11.0, J2,3=4.5, H-2); 3.14 (1H, ddd,
2
2
2J=17.0, J4,3=9.8, J4,3=4.6, H-4); 3.06 (1H, dt, J=17.0, J4,3=5.0, H-4); 2.55 (1H, dq, J=13.3,
J3,4=J3,2=4.8, H-3); 2.31 (1H, dtd, J=13.3, J3,2=J3,4=10.4, J3,4=4.8, H-3); 1.51 (9H, s, Bu). 13C NMR
2
t
δ: 193.0 (C-1); 187.8 (C=O dithiocarbonate); 143.5 (C-4a); 133.9 (C-6); 131.8 (C-8a); 128.7 (C-5);
t
t
128.1 (C-8); 126.9 (C-7); 51.55 (Cq Bu); 51.46 (C-2); 30.9 (C-3); 30.3 (3xCH3 Bu); 28.8 (C-4). FTIR
(neat): 1686 (C=O st. ketone); 1636 (C=O st. dithiocarbonate); 853. HRMS (ESI-TOF) m/z: [M +
Na]+ Calcd for C15H18O3NaO2S2 317.0640; Found 317.0640.
4.2.18. 2-{[(tert-Butylsulfanyl)(oxo-lambda4-sulfanylidene)methyl]sulfanyl}-1,2,3,4-
tetrahydronaphthalen-1-one 1t
By means of the same procedure as for 1q but only 1 eq. of m-CPBA was used, 339 mg
(28% yield) of the pure product were obtained as a colourless oil after purification by flash
column chromatography (eluted with DCM).
1H NMR δ: 8.05 (1H, dd, J8,7=7.9, J8,6=1.0, H-8); 7.51 (1H, td, J6,5=J6,7=7.5, J6,8=1.3, H-6);
7.34 (1H, t, J7,6=J7,8=7.6, H-7); 7.26 (1H, d, J5,6=7.7, H-5); 5.87 (1H, dd, J2,3=11.5, J2,3=4.6, H-2);
3.20 (1H, ddd, 2J=17.0, J4,3=10.5, J4,3=4.5, H-4); 3.09 (1H, dt, 2J=17.0, J4,3=4.7, H-4); 2.62 (1H, dq,
2J=13.1, J3,4=J3,2=4.7, H-3); 2.32 (1H, dddd, 2J=13.1, J3,2=11.4, J3,4=10.7, J3,4=4.6, H-3); 1.43 (9H, s,
tBu). 13C NMR δ: 192.7 (C-1); 179.2 (C=S=O); 143.3 (C-4a); 134.1 (C-6); 131.4 (C-8a); 128.8 (C-5);
t
t
128.0 (C-8); 127.1 (C-7); 51.8 (C-2); 50.5 (Cq Bu); 30.8 (3xCH3 Bu); 30.6 (C-3); 28.4 (C-4). FTIR
(neat): 1682 (C=O st.); 1120; 740 (Ar C-H bend. o.o.p.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C15H18NaO2S3 349.0361; Found 349.0361.
4.2.19. 2-(Benzoylsulfanyl)-1,2,3,4-tetrahydronaphthalen-1-one 1u
By means of the general procedure (using potassium thiobenzoate), 712 mg (91%
yield) of product were obtained as a white solid after purification by flash column
chromatography (eluted with 1:1 Hex:DCM).
3
3
1H NMR δ: 8.09 (1H, d, J8,7=7.8, H-8); 8.00 (2H, d, J=7.6, Ar(o) Bz); 7.59 (1H, t, J=7.4,
Ar(p) Bz); 7.52 (1H, t, J6,5=J6,7=7.4, H-6); 7.46 (2H, t, 3J=7.7, Ar(m) Bz); 7.34 (1H, t, J7,6=J7,8=7.6, H-
2
7); 7.28 (1H, d, J5,6=7.7, H-5); 4.76 (1H, dd, J2,3=11.6, J2,3=4.6, H-2); 3.24 (1H, ddd, J=16.9,
J4,3=10.7, J4,3=4.4, H-4); 3.11 (1H, dt, 2J=16.9, J4,3=4.5, H-4); 2.59 (1H, dq, 2J=13.2, J3,4=J3,2=4.6, H-
3); 2.38 (1H, qd, J= J3,4=J3,2=11.8, J3,4=4.4, H-3). 13C NMR δ: 193.5, 190.4 (C-1, C=O thioester);
2
143.6 (C-4a); 136.6 (Ar Cq Bz); 133.9 (C-6); 133.7 (Ar(p) Bz); 132.0 (C-8a); 128.8 (C-5); 128.7
(Ar(m) Bz); 128.1 (C-8); 127.5 (Ar(o) Bz); 127.0 (C-7); 50.9 (C-2); 31.0 (C-3); 29.2 (C-4). FTIR
(neat): 1686 (C=O st. ketone); 1662 (C=O st. thioester); 1207; 912, 687 (Ar C-H bend. o.o.p.).
M.p.=126°C. Anal. Calcd for C17H14O2S: C 72.32; H 5.00; S 11.35. Found: C 72.12; H 5.32; S
11.51.
4.2.20. 1-Oxo-1,2,3,4-tetrahydronaphthalen-2-yl benzenecarbodithioate 1v
By means of the general procedure (using sodium dithiobenzoate and 2-bromo-1-
tetralone ), 650 mg (72% yield) of product were obtained as a pink solid after purification by
flash column chromatography (eluted with 2:1 Hex:DCM).
14

3
1H NMR δ: 8.09 (1H, dd, J8,7=7.9, J8,6=1.1, H-8); 8.04 (2H, d, J=7.3, Ar(o) Bz); 7.56-7.51
3
(2H, m, H-6, Ar(p) Bz); 7.39 (2H, t, J=7.9, Ar(m) Bz); 7.35 (1H, t, J7,6=J7,8=7.5, H-7); 7.29 (1H, d,
2
J5,6=7.7, H-5); 5.26 (1H, dd, J2,3=12.3, J2,3=4.6, H-2); 3.28 (1H, ddd, J=16.9, J4,3=11.5, J4,3=4.4, H-
2
2
4); 3.10 (1H, dt, J=16.9, J4,3=4.2, H-4); 2.67 (1H, dq, J=13.0, J3,4=J3,2=4.4, H-3); 2.35 (1H, qd,
2J=J3,4=J3,2=12.3, J3,4=4.3, H-3). 13C NMR δ: 226.0 (C=S dithioester), 193.1 (C-1); 144.8 (Ar Cq Bz);
143.7 (C-4a); 134.1 (C-6); 132.7 (Ar(p) Bz); 132.1 (C-8a); 128.9 (C-5); 128.4 (Ar(m) Bz); 128.0 (C-
8); 127.1 (Ar(o) Bz); 127.0 (C-7); 58.3 (C-2); 29.7 (C-3); 29.4 (C-4). FTIR (neat): 1680 (C=O st.);
1215; 1041; 759, 739, 683 (Ar C-H bend. o.o.p.). M.p.=109°C. Anal. Calcd for C17H14OS2: C
68.42; H 4.73; S 21.49. Found: C 68.10; H 4.94; S 21.40.
4.2.21. 1-Oxo-1,2,3,4-tetrahydronaphthalen-2-yl pentanedithioate 1w
To a stirred solution of K2CO3 (1.2 eq., 370 mg) in dry acetone (5 mL) at 0°C under
argon atmosphere was added dithiopentanoic acid (1.2 eq., 360 mg) dropwise. After 15 min 2-
bromo-1-tetralone (500 mg, 2.2mmol) was added and stirring was continued at r.t. for 30min.
Afterward H2O (5 mL) was added and extracted with DCM (3x5mL). The combined organic
layers were dried with MgSO4 and evaporated to dryness. After purification by flash column
chromatography (eluted with 2:1 Hex:DCM), 483 mg (78%) of pure product were obtained as a
yellow greenish solid.
1H NMR δ: 8.06 (1H, d, J8,7=7.9, H-8); 7.52 (1H, td, J6,5=J6,7=7.5, J6,8=1.3, H-6); 7.33 (1H, t,
J7,6=J7,8=7.6, H-7); 7.27 (1H, d, J5,6=7.7, H-5); 5.10 (1H, dd, J2,3=12.4, J2,3=4.6, H-2); 3.24 (1H, ddd,
3
2
2J=16.9, J4,3=11.6, J4,3=4.4, H-4); 3.08 (2H, t, J=7.6, H-2’); 3.06 (1H, dt, J=17.0, J4,3=4.1, H-4);
2.57 (1H, dq, 2J=13.0, J3,4=J3,2=4.4, H-3); 2.26 (1H, qd, 2J=J3,4=J3,2=12.3, J3,4=4.3, H-3); 1.86 (2H, p,
3J=7.6, H-3’); 1.42 (2H, sex, J=7.4, H-4’); 0.94 (3H, t, J=7.4, H-5’). 13C NMR δ: 236.9 (C-1’);
193.1 (C-1); 143.6 (C-4a); 134.1 (C-6); 132.0 (C-8a); 128.8 (C-5); 127.9 (C-8); 126.9 (C-7); 57.5
(C-2); 51.7 (C-2’); 33.5 (C-3’); 29.5 (C-3); 29.4 (C-4); 22.0 (C-4’); 13.8 (C-5’). FTIR (neat): 1684
(C=O st.); 1304; 1218 (C=S st.); 893; 740 (Ar C-H bend. o.o.p.). M.p.=85°C. Anal. Calcd for
C15H18OS2: C 64.71; H 6.52; S 23.03. Found: C 65.00; H 6.22; S 23.08.
3
3
4.2.22. O,O-Diethyl
yl)sulfanyl]phosphonothioate 1x
[(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
To a stirred solution of K2CO3 (1.2 eq., 660 mg) in dry DMF (10 mL) at 0°C under argon
atmosphere was added O,O-diethyl dithiophosphate (1.2 eq., 1.1mL) dropwise. After 15 min 2-
bromo-1-tetralone (1.07g, 4.75mmol) was added and stirring was continued at r.t. for 2h.
Afterward NH4Cl aqueous saturated solution (20 mL) was added and extracted with DCM
(3x10mL). The combined organic layers were dried with MgSO4 and evaporated to dryness.
After purification by flash column chromatography (eluted with 1:1 Hex:DCM), 1.13g (72%) of
pure product were obtained as a colorless oil.
1H NMR δ: 8.04 (1H, d, J8,7=7.9, H-8); 7.50 (1H, td, J6,5=J6,7=7.5, J6,8=1.2, H-6); 7.33 (1H, t,
J7,6=J7,8=7.6, H-7); 7.25 (1H, d, J5,6=7.7, H-5); 4.36-4.14 (5H, m, H-2, 2xCH2 Et); 3.19-3.05 (2H, m,
2
2
H-4); 2.64 (1H, ddt, J=13.5, J=6.3, J=4.6, H-3); 2.37 (1H, tdd, J=13.5, J=8.9, J=4.9, H-3); 1.40
(3H, t, 3J=6.8, CH3 Et); 1.39 (3H, t, 3J=7.0, CH3 Et). 13C NMR δ: 192.9 (d, 3JC,P=7, C-1); 143.3 (C-4a);
2
134.0 (C-6); 131.5 (C-8a); 128.8 (C-5); 128.1 (C-8); 127.0 (C-7); 64.6 (d, JC,P=6, CH2 Et); 64.3 (d,
2
3
3
2JC,P=6, CH2 Et); 55.0 (d, JC,P=3, C-2); 31.7 (d, JC,P=4, C-3); 28.1 (C-4); 15.9 (d, JC,P=8, CH3 Et);
15.8 (d, 3JC,P=8, CH3 Et). 31P NMR δ: 93.0. FTIR (neat): 1684 (C=O st.); 1008, 957 (P-O-C st.); 652
(P=S st.). HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C14H20O3PS2 331.0586; Found 331.0588.
15

4.3. General procedure for the basic rearrangement of 2-oxo-carbonyl or thiocarbonyl
compounds 1
To a stirred solution of 1 (0.5 mmol) in dry THF (2 mL) at 0°C under argon atmosphere
was added NaH (1.6 eq., 13 mg). After 30 minutes of stirring at 0°C NH4Cl aqueous saturated
solution (5 mL) was added and extracted with Et2O (3x5mL). The combined organic layers were
dried with Na2SO4 and evaporated to dryness. Products were purified by chromatography
(preparative TLC).
4.3.1. Basic rearrangement of ethyl [(2-oxocyclohexyl)sulfanyl]methanethioate 1a7,12
By means of the general procedure, 55 mg (81% yield) of ethyl 2-hydroxy-5-
phenylcyclohex-1-ene-1-carbothioate13 2a were obtained as a yellow oil after purification by
chromatography (preparative plate eluting with Hex:AcOEt 95:5).
4.3.2. Basic rearrangement of ethyl [(2-oxocyclopentyl)sulfanyl]methanethioate 1b
By means of the general procedure, 44 mg (65% yield) of thionoester 2b were
obtained as a yellow solid after purification by chromatography (preparative plate eluting with
Hex:AcOEt 95:5).
4.3.2.1. Ethyl 2-hydroxycyclopent-1-ene-1-carbothioate 2b14
3
1H NMR δ: 12.97 (1H, s, OH); 4.53 (2H, q, J=7.1, CH2 Et); 2.65 (4H, t, 3J=7.6, H-3, H-5);
1.78 (2H, quint, 3J=7.6, H-4); 1.40 (3H, t, 3J=7.1, CH3 Et). 13C NMR δ: 205.3 (C=S); 181.3 (C-2);
111.9 (C-1); 65.3 (CH2 Et); 34.8, 28.9 (C-3, C-5); 17.6 (C-4); 13.9 (CH3 Et). FTIR (neat): 1204 (C-O-
C st., C=S st.). M.p.=43-44°C (lit. 48°C).
4.3.3. Basic
rearrangement
of
ethyl
[(3-methyl-2-
oxocyclohexyl)sulfanyl]methanethioate 1c
By means of the general procedure, 75 mg (79% yield) of thionoester 2c were obtained
as a yellow oil after purification by chromatography (preparative plate eluting with Hex:AcOEt
95:5).
4.3.3.1. Ethyl 2-hydroxy-3-methylcyclohex-1-ene-1-carbothioate 2c
3
1H NMR δ: 14.30 (0.5H, s, OH); 4.60-4.52 (1H, m, CH2 Et’, CH2 Et’’); 4.48 (1H, q, J=7.1,
CH2 Et); 3.82 (0.3H, dd, J3’,4’=12.7, J3’,4’=5.8, H-3’); 3.63 (0.2H, t, J3’’,4’’=4.9, H-3’); 2.76-1.37 (10H,
m); 1.25 (1.5H, d, JMe,3=7.1, H-3); 1.08 (0.6H, d, JMe’’,3’’=6.6, H-3’’); 1.25 (0.9H, d, JMe’,3’=6.5, H-3’).
13C NMR δ: 218.8 (C=S’); 218.1 (C=S’’); 209.1 (C-1’’); 207.7 (C-1’); 207.3 (C=S); 179.2 (C-2); 110.3
(C-1); 68.6 (CH2 Et’’); 68.4 (CH2 Et’); 67.1 (C-1’’); 65.7 (CH2 Et); 65.2 (C-1’); 46.0 (C-3’); 43.9 (C-
3’’); 35.1 (C-3); 36.5, 33.5, 24.5 (3xCH2’); 35.5, 32.4, 21.1 (3xCH2’’); 30.2, 24.6, 19.9 (3xCH2);
18.6 (Me); 15.1 (Me’’); 14.5 (Me’); 13.8 (CH3 Et); 13.54 (CH3 Et’); 13.45 (CH3 Et’’). FTIR (neat):
1206, 1175 (C-O-C st., C=S st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C10H16NaO2S 223.0763;
Found 223.0772.
4.3.4. Basic
rearrangement
of
ethyl
[(5-tert-butyl-2-
oxocyclohexyl)sulfanyl]methanethioate 1d
By means of the general procedure, 69 mg (93% yield) of thionoester 2d were obtained
as a yellow oil after purification by chromatography (preparative plate eluting with Hex:AcOEt
95:5).
16

4.3.4.1. Ethyl 5-tert-butyl-2-hydroxycyclohex-1-ene-1-carbothioate 2d
3
1H NMR δ: 14.12 (1H, s, OH); 4.51 (2H, q, J=7.1, CH2 Et); 2.61-2.55 (1H, m, H-6); 2.51-
2.35 (2H, m, H-3); 2.03-1.94 (1H, m, H-6); 1.88-1.83 (1H, m, H-4); 1.42 (3H, t, 3J=7.1, CH3 Et);
t
1.27-1.20 (2H, m, H-4, H-5); 0.91 (9H, s, Bu). 13C NMR δ: 207.3 (C=S); 175.8 (C-2); 110.4 (C-1);
t
t
65.7 (CH2 Et); 44.0 (C-5); 32.4 (Cq Bu); 32.1 (C-3); 27.3 (3xCH3 Bu); 25.4 (C-6); 22.8 (C-4); 13.8
(CH3 Et). FTIR (neat): 1581 (C=C st.), 1195 (C-O-C st., C=S st.). HRMS (ESI-TOF) m/z: [M + Na]+
Calcd for C13H22NaO2S 265.1233; Found 265.1232.
4.3.5. Basic
rearrangement
of
ethyl
[(2-oxo-5-
phenylcyclohexyl)sulfanyl]methanethioate 1e
By means of the general procedure, 96 mg (90% yield) of thionoester 2e were obtained
as a yellow oil after purification by chromatography (preparative plate eluting with Hex:AcOEt
95:5).
4.3.5.1. Ethyl 2-hydroxy-5-phenylcyclohex-1-ene-1-carbothioate 2e
1H NMR δ: 14.20 (1H, s, OH); 7.33 (2H, t, 3J=7.5, Ar(m)); 7.25-7.21 (3H, m, Ar(o, p)); 4.48
(2H, q, 3J=7.1, CH2 Et); 2.88-2.72 (2H, m, H-5, H-6); 2.65-2.49 (2H, m, H-3); 2.36 (1H, dd, 2J=15.7,
2
3
J6,5=10.9, H-6); 2.00 (1H, dtd, J=13.3, J=5.4, J=2.3, H-4); 1.92 (1H, m, H-4); 1.35 (3H, t, J=7.1,
CH3 Et). 13C NMR δ: 207.1 (C=S); 175.2 (C-2); 145.7 (Cq Ar); 128.6 (Ar(m)); 126.9 (Ar(p)); 126.5
(Ar(o)); 110.1 (C-1); 65.9 (CH2 Et); 40.2 (C-5); 32.3 (C-6); 31.4 (C-3); 28.3 (C-4); 13.8 (CH3 Et).
FTIR (neat): 1577 (C=C st.), 1206 (C-O-C st., C=S st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
4.3.6. Basic rearrangement of ethyl [(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]methanethioate 1f15
By means of the general procedure, 73 mg (92% yield) of thionoester 2f were obtained
as a yellow solid after purification by chromatography (preparative plate eluting with
Hex:AcOEt 95:5).
4.3.6.1. Ethyl 1-hydroxy-3,4-dihydronaphthalene-2-carbothioate 2f13
1H NMR δ: 14.53 (0.9H, s, OH); 8.04 (1H, d, J8’,7’=7.8, H-8’); 7.93 (0.9H, dd, J8,7=7.7,
J8,6=1.0, H-8); 7.48 (0.1H, td, J6’,5’=J6’,7’=7.5, J6’,8’=1.3; H-6’); 7.37-7.28 (1.9H, m, H-6, H-7, H-7’);
7.24 (0.1H, d, J5’,6’=7.5, H-5’); 7.17 (0.9H, d, J5,6=7.3, H-5); 4.64-4.58 (0.2H, m, CH2 Et’); 4.55
2
(1.8H, q, J=7.1; CH2 Et); 3.99 (0.1H, dd, J2’,3’=10.8, J2’,3’=4.7, H-2’); 3.10-2.89 (0.2H, m, H-4’);
2.81-2.72 (3.6H, m, H-3, H-4); 2.70-2.60 (0.1H, m, H-3’); 2.40 (0.1H, dq, 2J=13.5, J3,2=J3,4=4.6, H-
2
3); 1.32 (3H, t, J=7.1; CH2 Et). 13C NMR δ: 218.7 (C=S’); 206.2 (C=S); 193.1 (C-1’); 168.0 (C-1);
143.6 (C-4a'); 140.3 (C-4a); 133.7 (C-6’); 132.2 (C-8a'); 131.1 (C-6); 130.9 (C-8a); 128.8 (C-5’);
127.8 (C-8’); 127.3 (C-5); 126.9 (C-7’); 126.7 (C-8); 125.5 (C-7); 109.8 (C-2); 68.6 (CH2 Et’); 65.9
(CH2 Et); 64.2 (C-2’); 29.4 (C-3’); 27.9 (C-4’); 27.7, 22.1 (C-3, C-4); 13.9 (CH3 Et); 13.5 (CH3 Et’).
FTIR (neat): 1190, 1153 (C-O-C st., C=S st.). M.p.=73-74°C (lit. 69-70°C).
4.3.7. Basic rearrangement of ethyl {[(1S,5S,6R)-5-[(tert-butyldimethylsilyl)oxy]-2-oxo-
7-(prop-2-en-1-yl)-7-azabicyclo[4.1.0]heptan-3-yl]sulfanyl}methanethioate 1g
By means of the general procedure, 43 mg (94% yield) of thionoester 2g were obtained
as a yellow oil after purification by chromatography (preparative plate eluting with Hex:AcOEt
9:1).
17

4.3.7.1. Ethyl (1S,5S,6R)-5-[(tert-butyldimethylsilyl)oxy]-2-hydroxy-7-(prop-2-en-1-yl)-7-
azabicyclo[4.1.0]hept-2-ene-3-carbothioate 2g
1H NMR δ: 14.27 (1H, s, OH); 5.88 (1H, ddt, J2’,3’=17.2, J2’,3’=10.5, J2’,1’=5.4, H-2’); 5.39
(1H, d, J3’,2’=17.3, H-3’); 5.14 (1H, d, J3’,2’=10.5, H-3’); 4.53-4.41 (2H, m, CH2 Et); 3.95 (1H, dd,
J=10.1, J=6.5, H-5); 3.30 (1H, dd, 2J=14.6, J1’,2’=5.1 H-1’); 2.81-2.73 (2H, m, H-1’, H-4); 2.24-2.18
3
t
(3H, m, H-1, H-4, H-6); 1.38 (3H, t, J=7.1, CH3 Et); 0.93 (9H, s, Bu TBDMS); 0.11 (6H, 2xMe
TBDMS). 13C NMR δ: 206.1 (C=S); 172.8 (C-2); 134.1 (C-2’); 116.7 (C-3’); 106.6 (C-3); 67.3 (C-5);
t
t
65.9 (CH2 Et); 61.5 (C-1’); 47.7, 41.5 (C-1, C-6); 27.9 (C-4); 25.8 (3x CH3 Bu); 18.1 (Cq Bu); 13.7
ꢄ
(CH3 Et); -4.6, -4.7 (2xMe TBDMS). FTIR(NEAT): 1214 (C=S, C-O-C st.); 1092 (C-O-C st.). [∝]ꢀꢂꢃ ꢅ
=
-282 (c=0.4; DCM). HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C18H32NO3SSi 370.1867; Found
370.1862.
4.3.8. Basic rearrangement of ethyl [(2-oxocyclohex-3-en-1-yl)sulfanyl]methanethioate
1h
By means of the general procedure, 45 mg (75% yield) of 2h and 7 mg (11% yield) of
2h’ were obtained after purification by chromatography (preparative plate eluting with
Hex:AcOEt 9:1), both as yellow oils.
4.3.8.1. Ethyl 2-oxocyclohex-3-ene-1-carbothioate 2h
1H NMR δ: 14.20 (0.4H, s, OH’); 6.98 (0.6H, dt, J4,3=10.1, J4,5=3.8, H-4); 6.52 (0.4H, dt,
J
4’,3’=9.8, J4’,5’=4.4, H-4’); 6.10 (1H, dt, J3’,4’=9.9, J3’,5’=2.0, H-4’); 6.06 (1H, dt, J3,4=10.1, J3,5=2.0, H-
3
4); 4.63-4.53 (1.2H, m, CH2 Et); 4.51 (0.8H, q, J=7.1, CH2 Et’); 3.79 (0.6H, dd, J1,6=10.3, J1,6=4.8,
H-1); 2.62 (0.8H, t, J6’,5’=8.7, H-6’); 2.59-2.47 (1.2H, m, H-5, H-6); 2.45-2.35 (0.6H, m, H-5); 2.29-
2.22 (1.4H, m, H-6, H-5’); 1.412 (1.2H, t, 3J=7.1, CH3 Et’); 1.406 (1.8H, t, 3J=7.1, CH3 Et). 13C NMR
δ: 218.4 (C=S); 205.2 (C=S’); 194.5 (C-2); 169.1 (C-2’); 150.2 (C-4); 141.6 (C-4’); 129.4 (C-3);
125.6 (C-3’); 107.4 (C-1’); 68.6 (CH2 Et); 65.5 (CH2 Et’); 63.1 (C-1); 28.6 (C-6); 24.7 (C-5); 23.9 (C-
5’); 20.9 (C-6’); 13.9 (CH3 Et’); 13.5 (CH3 Et). FTIR (neat): 1218 (C=S st. C-O-C st.). HRMS (ESI-
TOF) m/z: [M + H]+ Calcd for C9H13O2S 185.0631; Found 185.0625.
4.3.8.2. Ethyl
4b-[(ethoxymethanethioyl)sulfanyl]-1,8a-dihydroxy-3,4,4a,4b,5,6,8a,8b-
octahydrobiphenylene-2-carbothioate 2h’
1H NMR δ: 14.46 (1H, s, OH enol); 5.86 (1H, dd, J7,8=10.1, J7,6=5.5, H-7); 5.55 (1H, d,
J8,7=10.1, H-7); 4.69-4.56 (2H, m, CH2 Et xanthate); 4.51 (2H, q, 3J=7.1, CH2 Et thionoester); 4.18
(1H, d, J8b,4a=9.2, H-8b); 3.69 (1H, s, OH); 3.57 (1H, ddd, J4a,4=12.0, J4a,8b=9.2, J4a,4=5.5, H-4a);
2.70 (1H, dt, 2J=16.3, J3,4=3.8, H-3); 2.42-2.29 (2H, m, H-5, H-6); 2.22-2.02 (3H, m, H-3, H-5, H-6);
3
3
1.82-1.68 (2H, m, H-4); 1.46 (3H, t, J=7.1, CH3 Et xanthate); 1.43 (3H, t, J=7.1, CH3 Et
thionoester). 13C NMR δ: 224.1 (C=S xanthate); 207.2 (C=S thionoester); 172.4 (C-1); 129.3 (C-
7); 128.3 (C-8); 112.9 (C-2); 81.8 (C-8a); 69.3 (CH2 Et xanthate); 68.1 (C-4b); 66.4 (CH2 Et
thionoester); 51.8 (C-8b); 40.5 (C-4a); 29.1 (C-4); 27.3 (C-5); 24.1 (C-3); 22.7 (C-6); 13.7 (CH3 Et
xanthate); 13.6 (CH3 Et thionoester). FTIR (neat): 1211 (C-O-C st., C=S st.). HRMS (ESI-TOF) m/z:
[M + Na]+ Calcd for C18H24NaO4S3 423.0729; Found 423.0719.
4.3.9. Basic rearrangement of 2-(acetylsulfanyl)-1-phenylpropan-1-one 1i
By means of the general procedure, 55 mg (88% yield) of 2-methyl-1-phenylbutane-
1,3-dione 2i16 were obtained as a yellow oil after purification by chromatography (preparative
plate eluting with Hex:AcOEt 8:2).
18

4.3.10. Basic rearrangement of 2-(acetylsulfanyl)-1-phenylethan-1-one 1j
By means of the general procedure, 76 mg (90% yield) of 3-hydroxy-1-phenylbut-2-en-
1-one 2j17 were obtained as a yellow oil after purification by chromatography (preparative
plate eluting with Hex:AcOEt 9:1).
4.3.11. Basic rearrangement of 6-(acetylsulfanyl)cyclohex-2-en-1-one 1k
By means of the general procedure, 27 mg (83% yield) of 2k were obtained as a yellow
oil after purification by chromatography (preparative plate eluting with DCM).
4.3.11.1. 6-Acetylcyclohex-2-en-1-one 2k
1H NMR δ: 15.86 (1H, s, OH’); 7.02 (1H, dt, J3,2=9.7, J3,4=3.5, H-3); 6.68 (1H, dt, J3’,2’=9.9,
J3’,4’=4.3, H-3’); 6.08-6.03 (2H, m, H-2, H-2’); 3.48 (1H, dd, J6,5=8.3, J6,5=5.1, H-6); 2.61-2.51 (1H,
m, H-5); 2.52 (2H, t, J5’,4’=7.7, H-5’); 2.41-2.30 (4H, m, H-4, H-4’); 2.27 (3H, s, CH3 Ac); 2.15-2.07
(1H, m, H-5); 2.10 (3H, s, CH3 Ac). 13C NMR δ: 205.0 (C=O Ac); 195.4 (C-1); 185.4, 183.4 (C-1’,
C=O Ac’); 151.4 (C-3); 145.3 (C-3’); 129.2, 127.8 (C-2, C-2’); 104.3 (C-6’); 60.2 (C-6); 30.0 (CH3
Ac); 24.4 (CH2); 24.3 (2XCH2); 22.0 (C-5’); 21.5 (CH3 Ac). FTIR (neat): 1716, 1673 (C=O st.). HRMS
(ESI-TOF) m/z: [M + H]+ Calcd for C8H11O2 139.0754; Found 139.0766.
4.3.12. Basic rearrangement of 2-(acetylsulfanyl)-4-tert-butylcyclohexan-1-one 1l
By means of the general procedure, 39 mg (91% yield) of 1-(5-tert-butyl-2-
hydroxycyclohex-1-en-1-yl)ethan-1-one 2l18 were obtained as a yellow oil.
4.3.13. Basic rearrangement of 2-(acetylsulfanyl)cyclooctan-1-one 1m
By means of the general procedure, 44 mg (95% yield) of 1-(2-hydroxycyclooct-1-en-1-
yl)ethan-1-one 2m19 were obtained as a yellow oil after purification by chromatography
(preparative plate eluting with Hex:AcOEt 9:1).
4.3.14. Basic rearrangement of 2-(acetylsulfanyl)cyclododecan-1-one 1n
By means of the general procedure, 49 mg (95% yield) of 2-acetylcyclododecan-1-one
2n were obtained as a yellow oil after purification by chromatography (preparative plate
eluting with Hex:AcOEt 9:1).
4.3.14.1. 2-Acetylcyclododecan-1-one 2n20
2
1H NMR δ: 3.82 (1H, dd, J2,3=11.5, J2,3=3.0, H-2); 2.63 (1H, ddd, J=16.0, J12,11=11.0,
2
J12,11=3.3, H-12); 2.41 (1H, ddd, J=16.2, J12,11=6.8, J12,11=3.3, H-12); 2.38 (0.5H, t, J12’,11’=7.3, H-
12’); 2.32 (0.5H, t, J3’,4’=7.1, H-3’); 2.25-2.18 (1H, m, H-3); 2.19 (0.75H, s, CH3 Ac’); 2.15 (3H, s,
CH3 Ac); 2.0-1.2 (17H + 16X0.25H, m). 13C NMR δ: 207.8, 204.7 (C-1, C=O Ac); 196.4, 190.4 (C-1’,
C=O Ac’); 110.2 (C-2’); 67.0 (C-2); 39.2 (C-12); 31.2 (C-12’); 28.66 (CH3 Ac); 24.39 (CH3 Ac’); 27.0,
25.4, 24.9, 24.44, 24.3, 24.2, 24.1 (9XCH2); 28.71, 26.2, 25.8, 25.1, 24.6, 24.1, 23.43, 22.25
(CH2’). FTIR (neat): 1697 (C=O st.).
4.3.15. Basic rearrangement of N,N-dimethyl-1-[(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]methanethioamide 1o
By means of the general procedure, except that the solvent used was DMF and the
reaction temperature was 60°C, 40 mg (91% yield) of 2o were obtained as a white solid after
purification by chromatography (preparative plate eluting with Hex:AcOEt 2:1).
19

4.3.15.1. N,N-Dimethyl-1-oxo-1,2,3,4-tetrahydronaphthalene-2-carbothioamide 2o
1H NMR δ: 8.03 (1H, d, J8,7=7.9, H-8); 7.49 (1H, t, J6,5=J6,7=7.1, H-6); 7.31 (1H, t,
J7,6=J7,8=7.6, H-7); 7.27 (1H, d, J5,6=6.9, H-5); 4.14 (1H, dd, J2,3=11.7, J2,3=4.6, H-2); 3.58 (3H, s,
Me); 3.35 (3H, s, Me); 3.17-3.02 (2H, m, H-4); 2.88 (1H, qd, 2J= J3,4=J3,2=12.2, J3,4=4.8, H-3); 2.35
2
(1H, dq, J=13.4, J3,4=J3,2=4.2, H-3). 13C NMR δ: 199.9 (C=S); 193.6 (C-1); 144.0 (C-4a); 133.8 (C-
6); 132.2 (C-8a); 128.8 (C-5); 127.9 (C-8); 126.8 (C-7); 58.3 (C-2); 44.7, 42.1 (2xMe); 30.5 (C-3);
28.8 (C-4). FTIR (neat): 1677 (C=O st.); 1517; 1277. M.p.=104-106°C. Anal. Calcd for C13H15NOS:
C 66.92; H 6.48; N 6.00; S 13.74. Found: C 66.90; H 6.80; N 6.27; S 13.92.
4.3.16. Basic rearrangement of 2-{[(tert-butylsulfanyl)methanethioyl]sulfanyl}-1,2,3,4-
tetrahydronaphthalen-1-one 1p
By means of the general procedure, 67 mg (95% yield) of 2p were obtained as a yellow
oil after purification by chromatography (preparative plate eluting with Hex:AcOEt 98:2).
4.3.16.1. 2-(tert-Butylsulfanylcarbothioyl)-1,2,3,4-tetrahydronaphthalen-1-one 2p
1H NMR δ: 16.21 (0.4H, s, OH’); 8.03 (0.6H, dd, J8,7=7.8, J8,6=0.8, H-8); 7.96 (0.4H, dd,
J8’,7’=7.7, J8’,6’=0.8, H-8’); 7.47 (0.6H, td, J6,5=J6,7=7.5, J6,8=1.3; H-6); 7.36 (0.4H, td, J6’,5’=J6’,7’=7.4,
J6’,8’=1.4; H-6’); 7.32-7.28 (1H, m, H-7, H-7’); 7.23 (0.6H, d, J5,6=7.7, H-5); 7.17 (0.4H, d, J5’,6’=7.4,
2
H-5’); 4.21 (0.6H, dd, J2,3=11.0, J2,3=4.7, H-2); 3.09 (0.6H, dt, J=16.7, J4,3=4.9, H-4); 3.02 (0.6H,
2
ddd, J=16.8, J4,3=10.1, J4,3=4.3, H-4); 2.95-2.91 (0.8H, m, H-3’); 2.83-2.73 (1.4H, m, H-3, H-4’);
2
t
t
2.36 (0.6H, dq, J=13.8, J3,2=J3,4=4.6, H-3); 1.70 (3.6H, s, Bu’); 1.63 (5.4H, s, Bu). 13C NMR δ:
234.4 (C=S); 216.3 (C=S’); 194.1 (C-1); 166.7 (C-1’); 143.6 (C-4a); 140.1 (C-4a'); 133.6 (C-6);
132.5 (C-8a); 131.4 (C-6’); 131.3 (C-8a'); 128.7 (C-5); 127.8 (C-8); 127.1 (C-5’); 126.90 (C-7’);
t
t
126.87 (C-7); 126.2 (C-8’); 117.5 (C-2’); 68.6 (C-2); 52.4 (Cq Bu); 51.8 (Cq Bu’); 31.3 (C-3); 29.3
t
t
(3xCH3 Bu’); 28.3 (C-4); 28.1 (3xCH3 Bu); 27.9 (C-4’); 26.0 (C-3’). FTIR (neat): 1521 (C=C st.);
1151 (C=S st.). HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C15H18NaOS2 301.0691; Found
301.0690.
4.3.17. Basic rearrangement of Ethyl [(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]formate 1q
By means of the general procedure, 31 mg (71% yield) of ethyl 1-hydroxy-3,4-
dihydronaphthalene-2-carboxylate 2q21 (yellow oil) and 8 mg (21% yield) of 2q’ (white solid)
were obtained after purification by chromatography (preparative plate eluting with Hex:AcOEt
8:2).
4.3.17.1. 3,3'',4,4''-Tetrahydro-1H,1''H-dispiro[naphthalene-2,2'-[1,3,5]trithiolane-
4',2''-naphthalene]-1,1''-dione 2q’
1H NMR δ: 8.14 (2H, d, J8,7=7.7, H-8); 7.51 (2H, t, J6,5=J6,7=7.5, H-6); 7.36 (2H, t,
2
J7,6=J7,8=7.6, H-7); 7.24 (2H, d, J5,6=7.7, H-5); 3.28 (2H, ddd, J=17.6; J4,3=8.6; J4,3=6.2, H-4); 3.18
2
(2H, dt, J=17.5, J4,3=4.8, H-4); 3.11-3.00 (4H, m, H-3). 13C NMR δ: 187.4 (C-1); 142.2 (C-4a);
133.9 (C-6); 130.5 (C-8a); 129.1 (C-8); 128.6 (C-9); 127.3 (C-7); 83.9 (C-2); 34.7 (C-3); 29.4 (C-4).
FTIR (neat): 1679 (C=O st.); 1286; 1212. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C20H16NaO2S3
407.0205; Found 407.0199.
4.3.18. Basic rearrangement of N,N-dimethyl-1-[(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]formamide 1r
20

By means of the general procedure, except that the solvent used was DMF and the
reaction temperature was 80°C, 70 mg (100%) of 2r were obtained as a yellow oil after
purification by chromatography (preparative plate eluting with DCM).
4.3.18.1. 2-({1-[(Dimethylcarbamoyl)oxy]-3,4-dihydronaphthalen-2-yl}disulfanyl)-3,4-
dihydronaphthalen-1-yl N,N-dimethylcarbamate 2r
1H NMR δ: 7.19-7.09 (8H, m, H-5, H-6, H-7, H-8); 3.17 (6H, s, Me); 3.03 (6H, s, Me);
2.94-2.89 (4H, m, H-4); 2.86-2.82 (4H, m, H-3). 13C NMR δ: 153.7 (C=O); 143.7, 135.8, 131.0,
126.6 (C-1, C-2, C-4a, C-8a); 128.1, 127.3, 124.4, 121.4 (C-5, C-6, C-7, C-8); 37.0, 36.5 (2xMe);
28.3 (C-4); 26.5 (C-3). FTIR (neat): 1721 (C=O st.); 1156 (C-O-C st.). HRMS (ESI-TOF) m/z: [M +
Na]+ Calcd for C26H28NaN2O4S2 519.1383; Found 519.1383.
4.3.19. Basic rearrangement of 2-{[(tert-butylsulfanyl)carbonyl]sulfanyl}-1,2,3,4-
tetrahydronaphthalen-1-one 1s
By means of the general procedure, 58 mg (65% yield) of 2s (yellow oil) and 10 mg
(13% yield) of 2s’ (yellow solid) were obtained after purification by chromatography
(preparative plate eluting with Hex:AcOEt 9:1).
4.3.19.1. (tert-Butylsulfanyl)(1-hydroxy-3,4-dihydronaphthalen-2-yl)methanone 2s
1H NMR δ: 13.72 (0.7H, s, OH); 8.03 (0.3H, d, J8’,7’=7.8, H-8’); 7.83 (0.7H, dd, J8,7=7.5,
J8,6=1.0, H-8); 7.47 (0.3H, td, J6’,5’=J6’,7’=7.5, J6’,8’=1.1; H-6’); 7.34-7.26 (1.7H, m, H-6, H-7, H-7’);
7.23 (0.3H, d, J5’,6’=7.7, H-5’); 7.16 (0.7H, d, J5,6=7.2, H-5); 3.67 (0.3H, dd, J2’,3’=9.0, J2,3=4.8, H-2’);
3.10 (0.3H, ddd, 2J=16.8, J4’,3’=6.9, J4’,3’=4.6, H-4’); 2.94 (0.3H, ddd, 2J=16.8, J4’,3’=8.6, J4’,3’=4.6, H-
2
4’); 2.82 (1.4H, t, J4,3=7.6, H-4); 2.57 (1.4H, t, J3,4=7.7, H-3); 2.50 (0.3H, qd, J= J3’,2’= J3’,4’=8.9,
2
t
J3’,4’=4.5, H-3’); 2.34 (0.3H, ddt, J=13.5, J3’,4’=7.0, J3’,4’=J3’,2’=4.8, H-3’); 1.56 (6.3H, s, Bu); 1.49
(2.7H, s, tBu’). 13C NMR δ: 197.9 (C=O thioester); 197.3 (C-1’); 193.6 (C=O thioester’); 163.2 (C-
1); 143.7 (C-4a'); 139.2 (C-4a); 133.9 (C-6’); 132.0 (C-8ª’); 130.8 (C-6); 130.1 (C-8a); 128.8 (C-5’);
127.7 (C-8’); 127.3 (C-5); 126.9 (C-7’); 126.7 (C-7); 125.0 (C-8); 106.5 (C-2’); 62.0 (C-2); 48.9 (Cq
t
t
t
tBu’); 48.2 (Cq Bu); 30.1 (3xCH3 Bu); 29.8 (3xCH3 Bu’); 27.9 (C-4); 27.4 (C-3’); 27.0 (C-4’); 21.7
(C-3). FTIR (neat): 1614, 1559 (C=O st., C=C st.); 1154; 1006; 805. HRMS (ESI-TOF) m/z: [M +
Na]+ Calcd for C15H18NaO2S 285.0920; Found 285.0920.
4.3.19.2. 2-(tert-Butylsulfanyl)naphthalen-1-ol 2s’
1H NMR δ: 8.27-8.24 (1H, m, H-8); 7.76-7.74 (1H, m, H-5); 7.56 (1H, d, J4,3=8.6, H-4);
7.52-7.47 (2H, m, H-6, H-7); 7.34 (1H, d, J3,4=8.6, H-3); 7.02 (1H, br s, OH); 1.33 (9H, s, tBu). 13
C
NMR δ: 153.2 (C-1); 135.1 (C-4a); 130.0 (C-3); 127.52, 127.46 (C-5, C-7); 125.8 (C-6); 124.1 (C-
t
t
8a); 122.8 (C-8); 120.3 (C-4); 115.1 (C-2); 49.1 (Cq Bu); 30.0 (3xCH3 Bu). FTIR (neat): 3445 (O-H
st.); 801 (Ar C-H bend. o.o.p.). HRMS (ESI-TOF) m/z: [M - tBu]+ Calcd for C10H7OS 175.0212;
Found 175.0213.
4.3.20. Basic
rearrangement
of
2-{[(tert-butylsulfanyl)(oxo-lambda4-
sulfanylidene)methyl]sulfanyl}-1,2,3,4-tetrahydronaphthalen-1-one 1t
By means of the general procedure, 49 mg (78% yield) of 2t (yellow solid) and 2 mg
(10% yield) of 2t’ (yellow oil) were obtained after purification by chromatography (preparative
plate eluting with Hex:AcOEt 9:1).
4.3.20.1. 2-(tert-Butylsulfanylcarbothioyl)-2-hydroxy-1,2,3,4-tetrahydronaphthalen-1-
one 2t
21

1H NMR δ: 8.03 (1H, d, J8,7=7.8, H-8); 7.50 (1H, td, J6,5=J6,7=7.5, J6,8=1.0; H-6); 7.34 (1H,
td, J7,6=J7,8=7.5, H-7); 7.23 (1H, d, J5,6=7.7, H-5); 4.95 (1H, s, OH); 3.15-3.03 (2H, m, H-4); 2.86
(1H, dt, 2J=13.6, J3,4=4.8, H-3); 2.30 (1H, ddd, 2J=13.6, J3,4=8.6, J3,4=6.2, H-3); 1.60 (9H, s, tBu). 13C
NMR δ: 238.3 (C=S); 196.6 (C-1); 143.7 (C-4a); 133.8 (C-6); 131.9 (C-8a); 128.8 (C-5); 127.8 (C-
t
8); 126.9 (C-7); 86.3 (C-2); 52.4 (Cq tBu); 36.8 (C-3); 28.2 (3xCH3 Bu); 26.2 (C-4). FTIR (neat):
3446 (O-H st.); 1686 (C=O st.); 1290; 1081 (C=S st.); 748 (Ar C-H bend. o.o.p.). M.p.= 75-77°C.
Anal. Calcd for C15H18O2S2: C 61.19; H 6.16; S 21.78. Found: C 60.90; H 6.41; S 21.60.
4.3.20.2. 2-(tert-Butylsulfanylcarbothioyl)naphthalen-1-ol 2t’
1H NMR δ: 14.16 (1H, s, OH); 8.51 (1H, d, J8,7=8.4, H-8); 8.13 (1H, td, J3,4=9.2, H-3); 7.71
(1H, d, J5,6=8.1, H-5); 7.60 (1H, td, J6,7=J6,5=7.5, J=1.1, H-6); 7.51 (1H, td, J7,6=J7,8=7.7, J=1.0, H-7);
t
7.19 (1H, d, J4,3=9.2, H-4); 1.75 (9H, s, Bu). 13C NMR δ: 225.4 (C=S); 159.4 (C-1); 136.4 (C-4a);
129.8 (C-6); 127.3 (C-5); 126.6 (C-8a); 126.0 (C-7); 125.2 (C-8); 122.7 (C-3); 121.5 (C-2); 117.8
t
t
(C-4); 53.0 (Cq Bu); 28.9 (3xCH3 Bu). FTIR (neat): 1623, 1562 (C=C st.); 1187, 1145 (C-O st., C=S
st.); 962, 801, 748 (Ar C-H bend. o.o.p.). HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C15H17OS2
277.0715; Found 277.0715.
4.3.21. Basic rearrangement of 2-(benzoylsulfanyl)-1,2,3,4-tetrahydronaphthalen-1-one
1u
By means of the general procedure, 97 mg (95% yield) of 2-benzoyl-3,4-
dihydronaphthalen-1-ol 2u22 were obtained as
a
yellow oil after purification by
chromatography (preparative plate eluting with Hex:AcOEt 9:1).
4.3.22. Basic
rearrangement
of
1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl
benzenecarbodithioate 1v
The general procedure was followed except that after 30 min of reaction methyl iodide
(1.5 eq) was added at 0°C and the reaction mixture was allowed to stir at the same
temperature for additional 30 min. The reaction mixture was treated as in the general
procedure and after purification by chromatography (preparative plate eluting with 1:2
Hex:DCM), 66mg (70% yield) of 2v were obtained as a yellow solid.
4.3.22.1. 2-[(Methylsulfanyl)(phenyl)methylidene]-1,2,3,4-tetrahydronaphthalen-1-
one 2v
1H NMR δ: 8.15 (1H, d, J8,7=7.6, H-8); 7.48-7.32 (5H, m, 5, 7, Ar(m,p) Ph); 7.19-7.15 (3H,
m, H-6, Ar(o) Bz); 2.82 (2H, t, J4,3=6.5, H-4); 2.51 (2H, t, J3,4=6.5, H-3); 1.75 (3H, s, Me). 13C NMR
δ: 187.0 (C-1); 156.2 (C-SMe); 142.6 (C-8a); 137.5 (Ar Cq Ph); 134.5 (C-4a); 132.5 (C-7); 128.9
(Ar(o) Ph); 128.0, 127.9, 127.8 (C-6, C-8, Ar(m,p) Ph); 127.6 (C-2); 126.9 (C-5); 30.0 (C-3); 29.4
(C-4); 16.8 (Me). FTIR (neat): 1638, 1596, 1522, 1484 (C=O st., C=C st.); 1303; 1240; 1218; 981,
888, 769, 743, 731, 701 (Ar C-H bend. o.o.p.). M.p.=138°C. Anal. Calcd for C18H16OS: C 77.11; H
5.75; S 11.43. Found: C 77.20; H 5.98; S 11.40.
4.3.23. Basic
rearrangement
of
1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl
pentanedithioate 1w
By means of the same procedure as for 1v, 60 mg (66% yield) of 2w were obtained as a
yellow oil after purification by chromatography (preparative plate eluting with 1:1 Hex:DCM).
4.3.23.1. 2-[1-(Methylsulfanyl)pentylidene]-1,2,3,4-tetrahydronaphthalen-1-one 2w
22

1H NMR δ: 8.08 (0.5H, dd, J8,7=7.8, J8,6=1.1, H-8); 8.05 (0.5H, dd, J8,7=7.9, J8,6=1.2, H-8);
7.40 (1H, td, J6,5=J6,7=7.4, J6,8=1.3, H-6); 7.31 (0.5H, td, J7,6=J7,8=7.5, J7,5=0.8, H-7); 7.30 (0.5H, td,
J7,6=J7,8=7.5, J7,5=1.0, H-7); 7.19 (1H, d, J5,6=7.5, H-5); 2.98-2.84 (5H, m, H-3, H-4, H-2’); 2.63 (1H,
t, 3J=8.0, H-2’); 2.39 (1.5H, s, Me); 2.35 (1.5H, s, Me); 1.64-143 (4H, m, H-3’, H-4’); 0.979 (1.5H,
3
3
t, J=7.1, H-5’); 0.976 (1.5H, t, J=7.3, H-5’). 13C NMR δ: 186.5, 185.8 (C-1); 157.8, 157.7 (C-1’);
142.8, 142.2 (C-8a); 135.1, 134.7 (C-4a); 132.3, 132.1 (C-6); 128.1, 126.0 (C-2); 128.0, 127.9 (C-
8); 127.8, 127.5 (C-5); 126.8, 126.7 (C-7); 32.0, 31.7 (C-3’); 31.2, 31.1 (C-2’); 29.7, 29.2, 29.0,
28.4 (C-3, C-4); 22.9, 22.7 (C-4’); 15.5, 14.0 (Me); 13.91, 13.89 (C-5’). FTIR (neat): 1639, 1597,
1525 (C=O st., C=C st.); 1296; 1224; 742 (Ar C-H bend. o.o.p.). HRMS (ESI-TOF) m/z: [M + H]+
Calcd for C16H21OS 261.1308; Found 261.1306.
4.3.24. Basic rearrangement of O,O-diethyl [(1-oxo-1,2,3,4-tetrahydronaphthalen-2-
yl)sulfanyl]phosphonothioate 1x
By means of the general procedure, 57 mg (95% yield) of 2x were obtained as a yellow
oil (preparative plate eluting with Hex:AcOEt 9:1).
4.3.24.1. Ethyl
ethoxy(sulfanylidene)phosphonite 2x
2-sulfanyl-3,4-dihydronaphthalen-1-yl
1H NMR δ: 7.62 (1H, d, J8,7=7.6, H-8); 7.21-7.08 (3H, m, H-5, H-6, H-7); 4.28-4.18 (4H, m,
2xCH2 Et); 3.62 (1H, s, SH); 2.85 (2H, t, J4,3=7.8, H-4); 2.57-2.52 (2H, m, H-3); 1.40 (6H, td, 3J=7.1,
4JH,P=0.8, 2xCH3 Et). 13C NMR δ: 140.0 (d, 2JC,P=9, C-1); 134.7 (d, 4JC,P=1, C-4a) 131.3 (d, 3JC,P=2, C-
8a); 126.99, 126.95, 126.3 (C-5, C-6, C-7); 121.6 (C-8); 118.9 (d, 3JC,P=8, C-2); 65.3 (d, 2JC,P=5, CH2
Et); 31.4 (d, 4JC,P=2, C-3); 28.1 (C-4); 15.9 (d, 3JC,P=8, CH3 Et). 31P NMR δ: 63.8. FTIR (neat): 1021,
969, 824 (P-O-C st.). HRMS (ESI-TOF) m/z: [M - H]+ Calcd for C14H18O3PS2 329.0429; Found
329.0430.
Aknowlegements
S. Silva thanks the FCT - Fundação para a Ciência e Tecnologia for the grant
SFRH/BD/84309/2012. This work was financially supported by: Project LISBOA-01-0145-FEDER-
007660 (Microbiologia Molecular, Estrutural e Celular) funded by FEDER funds through
COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by
national funds through FCT - Fundação para a Ciência e a Tecnologia. The NMR data was
acquired at CERMAX, ITQB-NOVA, Oeiras, Portugal with equipment funded by FCT - Fundação
para a Ciência e Tecnologia, project AAC 01/SAICT/2016.
References
1.
2.
Lightner, D. A.; Djerassi, C. Steroids 1963, 2, 583.
(a) Eschenmoser, A. Q Rev, Chem Soc 1970, 24, 366;
(b) Roth, M.; Dubs, P.;
Götschi, E.; Eschenmoser, A. Helv Chim Acta 1971, 54, 710;
Org. Synth. 1976, 55, 127.
(c) Loeliger, P.; Flueckiger, E.
3.
4.
Hussaini, S. R.; Chamala, R. R.; Wang, Z. Tetrahedron 2015, 71, 6017.
(a) Bridges, A. J.; Whitham, G. H. J Chem Soc, Perkin Trans 1 1975, 1603;
(b) Hamanaka, E. S. EP131374A1, 1985;
(c) Fabre, S.; Vila, X.; Zard, S. Z. Chem
Commun 2006, 4964; (d) Kazuo, T.; Masaharu, A.; Satoshi, O. Bull Chem Soc Jpn 1985, 58,
395; (e) Sakurai, O.; Ogiku, T.; Takahashi, M.; Hayashi, M.; Yamanaka, T.; Horikawa, H.;
Iwasaki, T. J Org Chem 1996, 61, 7889; (f) Sakurai, O.; Ogiku, T.; Takahashi, M.; Horikawa, H.;
Iwasaki, T. Tetrahedron Lett 1994, 35, 2187;
1980, 427;
(g) Sauve, J. P.; Lozach, N. Bull Soc Chim Fr
(h) Hoederath, W.; Hartke, K. Arch Pharm 1984, 317, 938;
(i)
23

Varacheberanger, M.; Nuhrich, A.; Devaux, G. Farmaco, Ed Sci 1987, 42, 465; (j) Ikegawa, S.;
Fishman, J. J Org Chem 1981, 46, 3747.
5.
Hegab, M. I.; Abdel-Megeid, F. M. E.; Gad, F. A.; Shiba, S. A.; Sotofte, I.; Moller,
J.; Senning, A. Acta Chem. Scand. 1999, 53, 133.
6.
Armarego, W. L. F.; Chai, C. L. L. Purification of Laboratory Chemicals;
Butterworth-Heinemann, 2003.
7.
Brown, M. D.; Gillon, D. W.; Meakins, G. D.; Whitham, G. H. J Chem Soc, Perkin
Trans 1 1985, 1623.
8.
Shindo, M.; Yoshimura, Y.; Hayashi, M.; Soejima, H.; Yoshikawa, T.;
Matsumoto, K.; Shishido, K. Org Lett 2007, 9, 1963.
9.
Aoyama, T.; Takido, T.; Kodomari, M. Synth Commun 2003, 33, 3817.
10.
11.
Haley, N. F.; Fichtner, M. W. J Org Chem 1980, 45, 175.
Alan Aitken, R.; P. Armstrong, D.; H. B. Galt, R.; T. E. Mesher, S. J Chem Soc,
Perkin Trans 1 1997, 2139.
12.
13.
Batanero, B.; Picazo, O.; Barba, F. J Org Chem 2001, 66, 320.
Purkayastha, M. L.; Chandrasekharam, M.; Vishwakarma, J. N.; Ila, H.;
Junjappa, H. Synthesis 1993, 1993, 245.
14.
15.
16.
17.
Palominos, M. A.; Rodriguez, R.; Vega, J. C. Chem Lett 1986, 15, 1251.
Anthore, L.; Zard, S. Z. Org Lett 2015, 17, 3058.
Matsukawa, Y.; Isobe, M.; Kotsuki, H.; Ichikawa, Y. J Org Chem 2005, 70, 5339.
Fargeas, V.; Baalouch, M.; Metay, E.; Baffreau, J.; Ménard, D.; Gosselin, P.;
Bergé, J.-P.; Barthomeuf, C.; Lebreton, J. Tetrahedron 2004, 60, 10359.
18.
Katritzky, A. R.; Pastor, A. J Org Chem 2000, 65, 3679.
19.
20.
21.
Kopp, F.; Stratton, C. F.; Akella, L. B.; Tan, D. S. Nat Chem Biol 2012, 8, 358.
Bolvig, S.; Hansen, P. E. Magn Reson Chem 1996, 34, 467.
Smith, A. M. R.; Rzepa, H. S.; White, A. J. P.; Billen, D.; Hii, K. K. J Org Chem
2010, 75, 3085.
22.
Rao, H. S. P.; Muthanna, N. Eur J Org Chem 2015, 2015, 1525.
24

Highlights
•
•
•
•
Method for the formation of 1,3-dicarbonyl compounds
Selective formation of O/S mixed 1,3-dicarbonyl compounds.
Regioselective
Readily available starting material.