Dithioester-enabled chemodivergent synthesis of acids, amides and isothiazoles via C[sbnd]C bond cleavage and C[sbnd]O/C[sbnd]N/C[sbnd]S bond formations under metal- and catalyst-free conditions

Article abstract of DOI:10.1016/j.tetlet.2017.05.064

An operationally simple and user-friendly process to access privileged scaffolds such as acids, amides and isothiazoles has been devised employing β-ketodithioesters for the first time. Remarkably, the new protocol involves combination of C[sbnd]C bond cl

Full text of DOI:10.1016/j.tetlet.2017.05.064

Accepted Manuscript
Dithioester-enabled chemodivergent synthesis of acids, amides and isothiazoles
via C-C bond cleavage and C-O/C-N/C-S bond formations under metal- and
catalyst-free conditions
Sonam Soni, Suvajit Koley, Maya Shankar Singh
PII:
S0040-4039(17)30645-7
DOI:
http://dx.doi.org/10.1016/j.tetlet.2017.05.064
TETL 48957
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
10 April 2017
13 May 2017
16 May 2017
Please cite this article as: Soni, S., Koley, S., Singh, M.S., Dithioester-enabled chemodivergent synthesis of acids,
amides and isothiazoles via C-C bond cleavage and C-O/C-N/C-S bond formations under metal- and catalyst-free
conditions, Tetrahedron Letters (2017), doi: http://dx.doi.org/10.1016/j.tetlet.2017.05.064
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. 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.

2
Graphical Abstract
To create your abstract, type over the instructions in the template box below.
Fonts or abstract dimensions should not be changed or altered.
Dithioester-enabled chemodivergent synthesis of
acids, amides and isothiazoles via C-C bond cleavage
and C-O/C-N/C-S bond formations under metal- and
catalyst-free conditions
Leave this area blank for abstract info.
Sonam Soni, Suvajit Koley, Maya Shankar Singh*

1
Tetrahedron Letters
Dithioester-enabled chemodivergent synthesis of acids, amides and isothiazoles
via C-C bond cleavage and C-O/C-N/C-S bond formations under metal- and
catalyst-free conditions
Sonam Soni, Suvajit Koley, Maya Shankar Singh
Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221 005, India
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
An operationally simple and user-friendly process to access privileged scaffolds such as acids,
amides and isothiazoles has been devised employing β-ketodithioesters for the first time.
Remarkably, the new protocol involves combination of CC bond cleavage and CO/CN/NS
bond formations in one-pot. Aqueous ammonia led to the formation of skeletally distinct amide
and isothiazole, whereas aqueous NaOH enabled the formation of aromatic acid near
quantitative yield. This practical approach, which can dramatically streamline the synthesis of
simple molecules, is highly chemoselective, cost-effective, amenable to gram scale, insensitive
to moisture as well as bears high functional group compatibility.
Available online
Keywords:
β-Ketodithioesters
Amides
© 2017 Elsevier Ltd. All rights reserved.
Isothiazoles
Acids
Vitamin B3
 Corresponding author.
E-mail address: mayashankarbhu@gmail.com (M. S. Singh)

2
The cleavage and formation of carbon-carbon and carbon-
heteroatom bonds are of fundamental importance in organic
synthesis, and lies at the heart of any chemical transformation.
These processes are essential prerequisites for a chemist to
venture into the synthesis of simple or complex molecules. Most
of the biologically active molecules contain carbon-heteroatom
bond, and their formation goes on continuously in-vivo involving
CC bond cleavage. However, in-vitro chemoselective cleavage
of CC bond has always been the challenging task due to its
inherent inert nature, thermodynamic stability and uncontrollable
selectivity.1 The cleavage of carbon-carbon bonds and the
simultaneous formation of carbon-heteroatom bonds facilitates
reorganization of an organic structure to new ones. Conventional
methods for the cleavage of inert CC bonds make use of harsh
conditions with stoichiometric oxidants such as peroxides and
toxic metal salts.2 Therefore, it is highly desirable and
challenging to develop milder, more efficient and general
protocols for the cleavage of CC bonds.
application in industry and pharmaceutical chemistry. The
aromatic amide foldamers are widely exploited for molecular
recognition, as these conformationally flexible aromatic amide
oligomers act as receptor.8 Therefore, the development of
efficient alternative route to prepare such compounds always
remains a regular practice to synthetic chemists. In this regard,
we herein disclose a metal-free, catalyst-free and oxidant-free
protocol for the cleavage of CC bond of β-ketodithioesters for
the first time (Scheme 1). This transformation has wide substrate
scope and proceeds with excellent chemoselectivity.
The pivotal example of C−C bond cleavage dates back more
than a half century. In the recent literature, many reactions have
been reported that involve formal C(CO)C(α) bond cleavage
with transition-metal based catalysts.3 Recently, Bathula and co-
workers4a reported iodine-catalyzed oxidative CC bond
cleavage of alkyl aryl ketones resulting to aromatic acids and
amides. Jiang et al.4b demonstrated oxidative cleavage and
esterification of CC bond of α-hydroxy ketones using K2CO3
and [18]-crown-6. Paine and co-workers4c reported the similar
cleavage of aryl-α-hydroxyketones using enzymes for the
synthesis of corresponding acids. Murakami and Ishida4d recently
reported the potential of metal-catalyzed C−C single bond
cleavage for organic synthesis. Wang and co-workers4e reported
two well-controlled transformations of β-oxodithioesters with
hydroxylamine to afford β-ketonitriles and isoxazoles,
respectively, under different reaction conditions. However, the
use of expensive and toxic metals along with equivalent amounts
of oxidants limits the application of such protocols in organic
synthesis. Consequently, development of metal-free and catalyst-
free strategies to cleave CC bond is a better alternative for
synthetic manipulations.
Scheme 1. Formation of amides, isothiazoles and acids from
-ketodithioesters.
-Ketodithioesters are not available commercially, but can be
easily synthesized from the reaction of enolates with
trithiocarbonate by literature method.9 Prompted by the awe-
inspiring chemistry of -ketodithioesters, we envisioned that
treatment of -ketodithioester with ammonia should form -
ketothioamide.6h Subsequently, we treated -ketodithioester 1h
(1 mmol) as a model substrate with the aqueous ammonium
hydroxide (25%, 10 ml) as a source of ammonia at room
temperature. After 24 h of stirring, work up of the reaction
mixture, unexpectedly provided two products which were
characterized as 4-methoxybenzamide 2f in 35% yield and 3-(4-
methoxyphenyl)-5-thiomethyl isothiazole 3f in 8% yield by
comparison with the reported ones.6d To our surprise, we did not
get even a trace of -ketothioamide (Table 1, entry 1). We
thought increase in temperature may furnish the desired
thioamide, so, we performed the reaction at elevated
temperatures. Reaction at 60 °C increased the yield of 4-
methoxybenzamide 2f to 56% with no trace of thioamide (Table
1, entry 2). Then, the above result encouraged us to optimize the
conditions for the formation of 4-methoxybenzamide 2f in high
yield. In this context, we performed the above model reaction at
100 °C. To our pleasure, we obtained the desired amide 2f in
88% yield within 12 h (Table 1, entry 3). However, the above
both conditions could not increase the yield of isothiazole 3f.
Inspired by the literature report,10 to increase the yield of
isothiazole, we treated dithioester 1h with a mixture of aq.
NH4OH (25%) and 1 equiv of Cu(OAc)2 at room temperature.
The reaction completed within 1 h forming Cu-dithioester
complex as a major product with a trace amount of both amide
and isothiazole (Table 1, entry 4).11 When 1h was treated with 8
N NaOH and 1 equiv of Cu(OAc)2 at room temperature, similar
result was obtained as in entry 4, except reaction took longer time
to complete (Table 1, entry 11). Further reaction of 1h at elevated
temperatures (60 and 100 0C) in the presence of 1 equiv of
Cu(OAc)2 could not provide the satisfactory result (Table 1,
entries 5 and 6). Then, we checked the effect of other Brønsted
bases like NaOH and KOH at different temperature without
promoter (Table 1, entries 7-10). NaOH (2 N) was found to be
ineffective for the reaction (Table 1, entry 7). Surprisingly,
NaOH (4 N) provided the 4-methoxy benzoic acid 4h in 55%
yield (Table 1, entry 8). To our great pleasure, 8 N NaOH
provided 4-methoxy benzoic acid 4h in quantitative yield (Table
Polyfunctional simple molecule-ketodithioester (KDTE) has
received significant attention in organic synthesis as a key
substrate.5 During the recent past, our group focused on the
reactivity of -ketodithioesters for the construction of skeletally
distinct heterocyclic frameworks via domino protocols.6
Recently, we reported selective cleavage of C(sp3)C(sp3) bond
of β-allyl-β-hydroxydithioesters catalyzed by Y(OTf)3.7 To our
knowledge, examples of metal-free CC bond cleavage of β-
ketodithioesters are rare. Consequently, exploring the metal-free
and catalyst-free protocol for CC bond cleavage of β-
ketodithioesters continues to be a challenging and valuable target.
Prompted by our previous report, and as a part of ongoing
synthetic quest to expand the frontiers of -ketodithioester
chemistry, we wish to disclose an expedient synthesis of aromatic
acids, aromatic amides and isothiazoles from a common
dithioester precursor via operationally simple one-pot cascade
process. To the best of our knowledge, no report is available until
date for the formation of amides and acids from β-
ketodithioesters.
The demand for improved synthetic methods towards aromatic
amides and aromatic acids is high and continuous. It is
noteworthy that amides and acids are the chief functionalities of
alkaloids, antibiotics, amino acids, vitamins, protein, nucleic
acids, neurotransmitters and polymers. They have been widely
utilized in strategic synthesis enabling their tremendous

3
1, entry 9). KOH also promoted the reaction in the desired
direction furnishing lower yield than NaOH (Table 1, entry 10).
Hence, the optimal condition for the synthesis of aromatic amide
2f was identified as 1.0 mmol of 1h and 10 ml of aq. NH3 (25%)
at 100 °C for 12 h (Table 1, entry 3). The optimal condition for
the synthesis of aromatic acid 4h was found to be 1.0 mmol of 1h
and 10 ml of aq. NaOH (8 N) at 100 °C (Table 1, entry 9). The
above reaction sequence indicates that the reaction of β-
ketodithioesters with aqueous ammonia or aqueous NaOH may
serve as an efficient route to aromatic amides or aromatic acids
for the first time.
aromatics such as naphthyl and biphenyl also worked well
under the optimized conditions. After successful utilization of
aromatic dithioesters, we next extended our study to
heteroaromatic dithioesters such as 2-furyl and 2-thienyl as R1
substituent, which enabled the corresponding amides in high
yields (Table 2, 2k, 2l). Pleasingly, the various groups such as
Me, MeO, Cl, Br, and CF3 at ortho, meta, and para-positions of
R1 moiety enabled the reaction to occur smoothly, resulting the
corresponding amides 2 in good yields. In all cases, we found the
isothiazole derivative as minor product with 5-15% yield. Our
various efforts to increase the yield of isothiazole derivatives
were futile and further efforts to optimize the conditions for
isothiazole are ongoing in our laboratory. Notably, -
oxodithioesters 1 bearing R2 moiety as various alkyl groups like
Me, Et, and iso-butyl were also well-tolerated under the optimal
reaction conditions toward the formation of isothiazole
derivatives albeit in low yield.
Table 1
Optimization of reaction conditions.a
Table 2
Substrate scope for the synthesis of 2 and 3.a
Entry
Base
Promoter
(1 equiv)
Temp Time
Yield (%)b
(10 ml)
(οC)
(h)
2f
35
3f
4h
nil
1
2
NH4OH
(25%)
NH4OH
(25%)
NH4OH
(25%)
NH4OH
(25%)
NH4OH
(25%)
NH4OH
(25%)
NaOH
(2 N)
nil
nil
rt
24
8
60
100
rt
18
12
1
56
88
7
5
nil
nil
3
nil
c
4
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
nil
trace trace
-
c
5
60
8
45
50
nil
nil
nil
nil
nil
15
20
nil
nil
nil
il
-
c
6
100
100
100
100
100
rt
6
-
7
24
24
10
10
6
trace
55
8
NaOH
(4 N)
nil
9
NaOH
(8 N)
nil
98
10
11
KOH
Nil
86
(8 N)
c
NaOH
(8 N)
Cu(OAc)2
nil
-
a 1.0 mmol of 1h and 10 ml of each base were used.
b Isolated yield.
a
All reactions were carried out using 1 mmol of 1 and 10 mL of
c
Copper complex with dithioester was formed as major
25% aqueous ammonium hydroxide.
product.11
b Isolated yield.
With the established optimal conditions in hand, we explored
the generality and scope of -ketodithioesters 1. A variety of -
ketodithioesters 1a–1r (see supporting information for details)
proved to be suitable substrates under the optimized reaction
conditions affording the desired aromatic amides 2 (Table 2, 13
examples, up to 90% yield) and thiazoles 3 (14 examples, up to
15% yield, Table 2). It is noteworthy that dithioesters 1 bearing
the substituents R1 not only aromatics (containing both electron-
donating as well as electron-withdrawing groups) but extended
To elaborate the scope of the reaction, dithioester 1s derived
from isopropyl methyl ketone and -substituted--ketodithioester
1t was subjected to standard reaction conditions. Treatment of
methyl 3-oxo-3-isopropylpropanedithioate 1s with 10 ml of aq.
NH3 (25%) at 100 °C afforded a complex reaction mixture of
several overlapping spots on TLC plate that could not be isolated.
This may be due to the decomposition of aliphatic dithioester at
100 0C. Treatment of methyl 3-oxo-2,3-diphenylpropanedithioate

4
1s under standard conditions furnished benzamide 2a in 76%
yield.
Treatment of -oxodithioesters 1 with 10 mL of aqueous 8 N
0
NaOH at 100 C furnished the corresponding acid in quantitative
yield (Table 3, 12 examples). As shown in Table 3, the selected
substrates 1 bearing both electron-donating and electron-
withdrawing aryl groups (R1 moiety) could efficiently afford the
corresponding aromatic acids 4a-4l at 100 0C in quantitative
yields. The variants of substituents in the phenyl ring (R1 moiety)
of dithioesters 1 did not hamper the reaction process, and the
approach tolerated dithioesters bearing both electron-donating
and electron-withdrawing groups. Different substituents such as
OMe, Me, Cl, Br, and CF3 at ortho-, meta-, and para-positions of
phenyl ring were found to be compatible (Table 3, 4a-4l).
Notably, dithioester bearing heteroaromatic 2-furyl group at R1
moiety was also tolerated well furnishing the corresponding acid
in 95% yield (Table 3, 4k). It is noteworthy that dithioester
bearing extended aromatic moiety such as 2-naphthyl group at R1
moiety also worked well under the optimized conditions
affording the corresponding acid in 98% yield (Table 3, 4l).
Scheme 2. Preparation of vitamin B3.
The structures of all the synthesized aromatic amides (2a-2n)
and aromatic acids (4a-4l and 4m) were confirmed by their
satisfactory spectral (1H & 13C NMR) studies and comparision
with the reported ones. The compounds 3,5-disubstituted
isothiazoles were characterised by their satisfactory spectral (1H
&
13C NMR and HRMS) studies and comparision with the
reported ones.6d
By taking our entire experimental outcomes into
consideration, a plausible reaction mechanism for the formation
of amides 2, isothiazoles 3 and acids 4 is depicted in Scheme 3.
The first step is believed to be the attack of nitrogen/oxygen
nucleophile (ammonia or hydroxide ion) to the β-carbonyl carbon
of dithioester to generate intermediates A and E, respectively.
The high preference for nucleophilic attack to -carbonyl carbon
over thiocarbonyl carbon of dithioester is rather remarkable
under the present reaction conditions.6h The intermediate A can
undergo base promoted CC bond cleavage to form the amide 2
(Path I) with the elimination of one molecule of alkyl
dithioacetate; or it may undergo dehydration to form the acyclic
Further dithioester 1s derived from isopropyl methyl ketone
and -substituted--ketodithioester 1t was subjected to optimized
reaction conditions. Treatment of alkyl dithioester 1s with 10 mL
0
of aqueous 8 N NaOH at 100 C afforded a complex reaction
mixture of several overlapping spots on TLC plate that could not
be isolated, could be due to the decomposition of aliphatic
dithioester at 100 0C. Treatment of methyl 3-oxo-2,3-
diphenylpropanedithioate 1s under standard conditions furnished
benzoic acid 4a in 92% yield.
imine intermediate
C
(Path II). The β-iminodithioester
intermediate C undergoes intramolecular S-cyclization6d to form
cyclic intermediate D, which finally undergoes aerial oxidation to
give the isothiazole moiety 3. The β-gemdiol intermediate E
formed by the reaction of NaOH undergoes base promoted CC
bond cleavage to give acid 4 with the elimination of one
molecule of alkyl dithioacetate. This strategy provides access to
diverse amides and acids in near-quantitative yields in
remarkably cost-effective manner, which is otherwise difficult to
obtain.
Table 3
Substrate scope for the synthesis of 4.a
Scheme 3. Plausible mechanism for the formation of acids,
amides, and isothiazoles from β-ketodithioesters.
In summary, we have developed a straightforward base-
controlled chemoselective formation of aromatic acids, aromatic
a
amides, and isothiazoles from
a common precursor β-
All reactions were carried out using 1 mmol of 1 and 10 mL of
ketodithioester via operationally simple one-pot cascade process.
This general protocol proceeded smoothly under metal-free and
catalyst-free reaction conditions, and is characterized by having
an ample substrate scope and broad functional group tolerance.
This clean and facile protocol would be valuable supplement to
the traditional methods for the formation of acids and amides that
could be of immense value for both synthetic and medicinal
chemists. This strategy would broaden the chemistry of β-
oxodithioesters and hold great potential in the concise formation
of diverse useful acids and amides. More importantly, we have
reported an easy route for the formation of vitamin B3 one of the
essential human nutrients. I strongly suggest comparisons to the
8 N aq. NaOH solution.
b Isolated yield.
After preparation of diverse useful acids in quantitative yield,
we tried to synthesize vitamin B3 (nicotinic acid) using this
operationally simple and inexpensive strategy. Consequently, we
treated methyl-3-oxo-3-(pyridin-3-yl)propanedithioate 1p under
optimized conditions. To our great satisfaction, the desired acid
pyridine-3-carboxylic acid (vitamin B3) 4m was obtained in 98%
yield within 10 h with high purity (Scheme 2).

5
(d) Shukla G, Srivastava A, Singh MS. Org. Lett. 2016;18:2451-
2454;
haloform reaction that generates carboxylic acids or amides, but
only with stoichiometric halides.
(e) Koley S, Chanda T, Ramulu BJ, Chowdhury S, Singh MS.
Adv. Synth. Catal. 2016;358:1195-1201;
(f) Ramulu BJ, Koley S, Singh MS. Org. Biomol. Chem.
2016;14:434-439;
Acknowledgments
(g) Nagaraju A, Ramulu BJ, Shukla G, Srivastava A, Verma GK,
Raghuvanshi K, Singh MS. Green Chem. 2015;17:950-958;
(h) Samai S, Chanda T, Ila H, Singh MS, Eur. J. Org. Chem.
2013;4026-4031;
(i) Nandi GC, Samai S, Singh MS. J. Org. Chem. 2011;76:8009-
8014.
We gratefully acknowledge the generous financial support
from the Science and Engineering Research Board
(SERB/EMR/2015/002482) and the Council of Scientific and
Industrial Research (02(0263)/16/EMR-II), New Delhi, India.
7. Chowdhury S, Chanda T, Nandi GC, Koley S, Ramulu BJ, Pandey
K, Singh MS. Tetrahedron 2013;69:8899-8903.
8. Zhang DW, Zhao X, Hou JL, Li ZT. Chem. Rev. 2012;112:5271-
5316.
9. Samuel R, Asokan CV, Suma S, Chandran P, Retnamma S,
Anabha ER, Tetrahedron Lett. 2007;48:8376-8378.
10. Xu H, Wolf C. Chem Commun. 2009;3035-3037.
11. Saumweber R, Robl C, Weigand W. Inorg. Chim. Acta 1998;269:
83-90.
Supplementary data
Supplementary data associated with this article can be found,
in the online version at
References and notes
1. (a) Zhou Y, Rao C, Mai S, Song Q. J. Org. Chem. 2016;81:2027-
2034;
(b) Xing Q, Lv H, Xia C, Li F. Chem. Commun. 2016;52:489-492;
(c) Ding W, Song Q. Org. Chem. Front. 2015;2:765-770;
(d) Gazi S, Ng WKH, Ganguly R, Moeljadi AMP, Hirao H, Soo
HS. Chem. Sci. 2015;6:7130-7142.
2. (a) Tang C, Jiao N. Angew. Chem. Int. Ed. 2014;53:6528-6532;
(b) Sharif M, Chen J, Langer P, Bellera M, Wu XF. Org. Biomol.
Chem. 2014;12:6359-6362;
(c) Sarma MJ, Borah AJ, Rajbongshi KK, Phukan P. Tetrahedron
Lett. 2015;56:7008-7011;
(d) Huang X, Li X, Zou M, Song S, Tang C, Yuan Y, Jiao N. J.
Am. Chem. Soc. 2014;136:14858-14865.
3. (a) Wang P, Liao S, Zhu JB, Tang Y. Org. Lett. 2013;15:3606-
3609;
(b) Crabtree RH, Dion RP, Gibboni DJ, McCrath DV, Holt EM. J.
Am. Chem. Soc. 1986;108:7222-7227;
(c) Deng L, Xu T, Li H, Dong G. J. Am. Chem. Soc.
2016;138:369-374;
(d) Youn SW, Kim BS, Jagdale AR. J. Am. Chem. Soc.
2012;134:11308-11311;
(e) Ohmura T, Taniguchi H, Suginome M. ACS Catal.
2015;5:3074-3077;
(f) Jun CH. Chem. Soc. Rev. 2004;33:610-618;
(g) Park YJ, Park JW, Jun CH. Acc. Chem. Res. 2008;41:222-234;
(h) Zhang L, Bi X, Guan X, Li X, Liu Q, Barry QD, Liao P.
Angew. Chem. Int. Ed. 2013;52:11303-11307.
4. (a) Sathyanarayana P, Upare A, Ravi O, Muktapuram PR, Bathula
SR. RSC Adv. 2016;6:22749-22753;
(b) Liu H, Dong C, Zhang Z, Wu P, Jiang X. Angew. Chem. Int.
Ed. 2012;51:12570-12574;
(c) Paria S, Halder P, Paine TK. Angew. Chem. Int. Ed. 2012;51:
6195-6199;
(d) Murakami M, Ishida N. J. Am. Chem. Soc. 2016;138: 13759-
13769.
(e) Li J, Ma W, Ming W, Cong Xu C, Wei N, Wang W. J. Org.
Chem. 2015;80: 11138-11142.
5. (a) Singh MS, Nandi GC, Chanda T. RSC Adv. 2013;3:14183-
14198 and references therein;
(b) Wen LR, Li ZR, Li M, Cao H. Green Chem. 2012;14:707-716;
(c) Wen LR, Yuan WK, Li M. J. Org. Chem. 2015;80:4942-4949;
(d) Koley S, Chanda T, Samai S, Singh MS. J. Org. Chem.
2016;81:11594-11602;
(e) Nandi GC, Samai S, Singh MS, Ila H, Junjappa H. Eur. J. Org.
Chem. 2012;967-974;
(f) Rahman A, Ila H, Junjappa H. Synthesis 1984;3:250-252;
(g) Peruncheralathan S, Khan TA, Ila H, Junjappa H. J. Org.
Chem. 2005;70:10030-10035.
(h) Sridhar M, Kurva S, Sriramoju V, Nanubolu JB, Cirandur SR.
RSC Adv. 2015;5:64797-64801.
(i) Kumara CSP, Gowda GB, Ramesh N, Sadashiva MP, Junjappa
H. Tetrahedron Lett. 2016;57:2520-2523.
6. (a) Nandi GC, Samai S, Singh MS. J. Org. Chem. 2010;75:7785-
7795;
(b) Verma RK, Verma GK, Shukla G, Nagaraju A, Singh MS.
ACS Comb. Sci. 2012;14:224-230;
(c) Srivastava A, Shukla G, Singh MS. Tetrahedron 2017;73:879-
887;

6
Highlights
 Base-controlled chemoselective formation
of acids & amides from -ketodithioesters
 One-pot, metal- and catalyst-free conditions
 Ample substrate scope and broad functional
group tolerance
 More importantly, an easy route for the
formation of vitamin B3 is reported