Nickel-Catalyzed Difunctionalization of Alkynyl Bromides with Thiosulfonates and N -Arylthio Succinimides: A Convenient Synthesis of 1,2-Thiosulfonylethenes and 1,1-Dithioethenes

SYNTHESIS

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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart

2021, 53, A–O

paper

A

en

A. H. Kumari et al.

Paper

Synthesis

Nickel-Catalyzed Difunctionalization of Alkynyl Bromides with

Thiosulfonates and N-Arylthio Succinimides: A Convenient

Synthesis of 1,2-Thiosulfonylethenes and 1,1-Dithioethenes

Arram Haritha Kumari^a

O

S

Ar¹

S

O

Ar

S

O

Jangam Jagadesh Kumar^a

Gamidi Rama Krishna^b

Raju Jannapu Reddy*^a

N

S

O

S

Ar²

Br

R

Ar¹

S

R

O

R

NiCl₂·6H₂O (5 mol%)

Cs₂CO₃, DMF, N₂

S

90 °C, 2 h

90 °C, 3 h

Ar

Ar²

Geminal disulfenylation

69–88% (10 examples)

Vicinal thiosulfonylation

37–79% (49 examples)

Stereoselective trisubstituted olefins

Wide substrate scope

^aDepartment of Chemistry, University College of Science,

Osmania University, Hyderabad 500 007, India

rajuchem77@osmania.ac.in

Readily available starting materials

rajuchem08@yahoo.co.in

https://www.rjreddyresearchgroup.com/

^bX-ray Crystallography, CSIR-National Chemical Laboratory,

Pune 411 008, India

Corresponding Author

Received: 03.03.2021

Accepted after revision: 14.04.2021

Published online: 14.04.2021

Organosulfur compounds⁵containing sulfone and thio-

ether moieties are attractive compounds in organic synthe-

sis⁶and the pharmaceutical industry.⁷Recently, thiosulfon-

ates (RS–SO₂R¹)^8–10have been utilized to install two distinct

C–S bonds (sulfenyl and sulfonyl) in alkenes and alkynes

through atom transfer thiosulfonylation.^9,10Compared to

the thiosulfonylation of alkenes,⁹investigations of alkynes

and their equivalents are considerably limited, probably

due to stereo- and regioselective concerns.¹⁰In this context,

Xu and co-workers developed the first example of the atom

transfer thiosulfonylation of alkynes using PhSO₂SR and a

combination of an Au/Ru-catalytic system under visible-

light irradiation (Scheme 1, a).^10aSubsequently, our group

employed the Cs₂CO₃-mediated vicinal thiosulfonylation of

1,1-dibromo-1-alkenes with thiosulfonates, leading to a re-

versal of regioselectivity in the thiosulfonylated products

(Scheme 1, b).^10cVery recently, the Jia group successfully

disclosed the visible-light-driven atom transfer radical ad-

dition of aryl alkynes with thiosulfonates under the catalyt-

ic influence of Eosin Y to furnish the desired vinyl thiosul-

fones with the same regioselectivity (Scheme 1, c).^10dRe-

gardless of these innovative approaches, the use of

expensive reagents and prolonged reaction times were dis-

advantages in their scale-up synthesis. Therefore, a general,

mild and robust vicinal thiosulfonylation using a cheap and

readily available catalyst is still desirable. Accordingly, we

envisioned that alkynyl bromides would be alternative

starting materials for the regioselective construction of two

different C–S bonds on the vicinal carbons in a single opera-

tion (Scheme 1, d).

DOI: 10.1055/a-1482-2486; Art ID: ss-2021-z0105-op

Abstract An efficient nickel-catalyzed vicinal thiosulfonylation of 1-

bromoalkynes with thiosulfonates in the presence of cesium carbonate

is described. An operationally simple and highly regioselective atom

transfer radical addition (ATRA) of alkynyl bromides provides a wide

range of (E)-1,2-thiosulfonylethenes (-aryl--thioarylvinyl sulfones) in

moderate to high yields. The extensive substrate scope of both alkynyl

bromides and thiosulfonates is explored with a broad range of function-

al groups. Indole-derived 1,1-bromoalkenes were also successfully ex-

plored in this 1,2-thiosulfonylation process. Moreover, the nickel-cata-

lyzed geminal-dithiolation of alkynyl bromides with N-arylthio

succinimides provides 1,1-dithioalkenes in high yields. The present pro-

tocol is reliable on gram scale, and a sequential one-pot bromination

and thiosulfonylation of phenylacetylene is achieved in a scale-up syn-

thesis. Following control experiments, a plausible mechanism is pro-

posed to rationalize the experimental outcome and the vicinal thio-

sulfonylation.

Key words alkynyl bromides, atom transfer radical addition (ATRA),

thiosulfonylation, thiosulfonates, vinyl thiosulfones

Stereoselective vicinal difunctionalization of carbon–

carbon multiple bonds represents an attractive strategy for

the rapid construction of molecular complexity from sim-

ple starting materials.¹Of the many catalytic difunctional-

izations, Ni-catalyzed difunctionalization has emerged to

introduce two functional groups across an unsaturated car-

bon–carbon bond in a one-step operation.²Atom transfer

radical addition (ATRA)³has been recognized as a powerful

approach for installing two functional groups on the vicinal

carbons of a -system, a process generally known as

Kharasch addition.⁴Despite these achievements, installing

diverse functional groups on alkynes in a rapid, flexible and

efficient manner in order to generate highly substituted

alkenes remains a challenging task.

Generally, alkynyl bromides are versatile building

blocks, and their chemistry has been widely explored in or-

ganic synthesis.¹¹As a result, we were interested in investi-

gating the atom transfer thiosulfonylation of alkynyl bro-

mides with thiosulfonates in order to furnish vinyl thiosul-

fone products whilst delivering the anticipated

Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B

A. H. Kumari et al.

Paper

Synthesis

Eosin Y and Eosin B gave 3aa in lower yields compared with

the conventional procedure (see Table S2 in the Supporting

Information). No reaction was observed in the absence of

Cs₂CO₃, thus indicating that the role of Cs₂CO₃was crucial

for this transformation (entry 15).

(a) Xu et al., ACS Catal. 2018, 8, 8237 & Tetrahedron Lett. 2019, 60, 916

SR

O

R²

Ph₃PAuNTf₂(0.5 mol%)

S

R

R¹

R²

+

Ph

S

Ru(bpy)₃Cl₂(0.1 mol%)

Dioxane, hν, N₂, rt

SO₂Ph

(b) Our previous work: Adv. Synth. Catal. 2019, 361, 1587

SO₂Ar¹

O

Ar¹

Br

Cs₂CO₃, DMF

N₂, 90 °C, 3 h

Ar

S

Ar²

Ar

+

S

SAr²

Br

(c) Jia et al., Org. Lett. 2020, 22, 5885

Table 1 Optimization of the Vicinal Thiosulfonylation Using 1-Bro-

moalkyne 1a with S-Phenyl Thiosulfonate 2a^a

SO₂Ar¹

O

Ar¹

Eosin Y (1 mol%), KOH

S

Ar²

Ar

S

+

DMA, rt, 12 h, white LEDs

SAr²

Ar¹

(d) Present work

SO₂Ph

MeO

O

S

O

MeO

Ar

S

O

reaction conditions

N

S

Ph

O

Br

+

S

Ar²

Ph

S

Br

R

Ar¹

SPh

(E)-3aa

Cs₂CO₃, DMF, 90 °C

S

O

R

MeO

R

NiCl₂·6H₂O (5 mol%)

Cs₂CO₃, DMF, N₂

1a (1.0 equiv) 2a (1.5 equiv)

S

90 °C, 3 h

90 °C, 2 h

S

Ar²

Ar

Geminal disulfenylation

Vicinal thiosulfonylation

Entry Catalyst (mol%)

Cs₂CO₃

Time

Yield of 3aa^bE/Z^c

19:1

Scheme 1 Representative vicinal thiosulfonylations through atom

transfer radical addition (ATRA)

1

2

none

4 equiv

3 equiv

2 equiv

3 equiv

none

6 h

4 h

3 h

5 h

16 h

24 h

39%

59%

53%

72%

75%

81%

71%

58%

69%

72%

59%

67%

55%

61%

trace

CuClO₄·6H₂O (20 mol%)

CuSO₄·5H₂O (20 mol%)

NiCl₂·6H₂O (20 mol%)

NiCl₂·6H₂O (10 mol%)

NiCl₂·6H₂O (5 mol%)

NiCl₂(PPh₃)₂(5 mol%)

Ni(dppp)Cl₂(5 mol%)

NiBr₂·6H₂O (5 mol%)

NiClO₄·6H₂O (5 mol%)

NiCl₂·6H₂O (5 mol%)

25:1

30:1

25:1

30:1

25:1

20:1

Nd

3

regioselectivity. In continuation of our interest in organo-

sulfur chemistry¹²and thiosulfonates,^{10c,12c,12e–i}we report

herein an efficient Ni-catalyzed intermolecular vicinal thio-

sulfonylation of alkynyl bromides with thiosulfonates un-

der mild conditions. A variety of substrates was explored al-

lowing the synthesis of a wide range of (E)-1,2-thiosulfony-

lethenes. In addition, the methodology was further applied

to the synthesis of 1,1-dithioalkenes in high yields. From a

synthetic point of view, the present protocol has also been

achieved on gram scale.

4

5

6

7

8

9

10

11

12^d

13^e

14^f

15

Our investigations began with 4-(bromoethynyl)-1,2-di-

methoxybenzene (1a) and S-phenyl benzenesulfonothioate

(2a) as model substrates (Table 1). An extensive survey of

the reaction conditions was undertaken by investigating

different parameters, including the catalyst, solvent, tem-

perature, concentration, etc. (see Table S1 in the Supporting

Information). An initial experiment was performed at 90 °C

for the thiosulfonylation of 1a with 2a in the presence of

Cs₂CO₃, which gave the desired product 3aa in 39% yield

(entry 1). Next, the copper-catalyzed thiosulfonylation af-

forded a slightly improved yield of product 3aa (entries 2

and 3). To our surprise, the NiCl₂·6H₂O-catalyzed vicinal

thiosulfonylation proceeded smoothly with 3 equivalents of

Cs₂CO₃in DMF at 90 °C (entries 4–6). The use of 5 mol% of

NiCl₂·6H₂O afforded the thiosulfonylated product 3aa in

81% yield with excellent stereoselectivity (entry 6). Inspired

by these results, we screened different Ni catalysts, howev-

er, none of these proved beneficial in improving the yield of

3aa (entries 7–10). Lowering the amount of Cs₂CO₃, elevat-

ing the temperature or performing the reaction under aero-

bic conditions were unsuccessful in giving better outcomes

(entries 11–13). Next, our attention turned to developing a

visible-light-induced thiosulfonylation under the influence

of an organic dye as the photocatalyst. Gratifyingly, the

standard reaction performed with Rose Bengal (RB) (2

mol%) under irradiation with blue LEDs for 16 hours led to

the desired product 3aa, albeit in only 61% yield (entry 14).

Disappointingly, our subsequent efforts using Rose Bengal,

–

^aUnless otherwise specified, all reactions were performed on a 0.2 mmol

scale of 1a (1.0 equiv), 2a (1.5 equiv), catalyst (5–20 mol%) and Cs₂CO₃(2 to

4 equiv) in anhydrous DMF (1 mL) under N₂at 90 °C.

^bIsolated yield.

^cE/Z mixture based on ¹H NMR analysis; nd = not determined.

^dReaction at 110 °C.

^eReaction under an O₂atmosphere.

^fIrradiation with blue LEDs in the presence of Rose Bengal (2 mol%) at room

temperature.

With optimized reaction conditions in hand (see Table

1, entry 6), we next explored the generality of the vicinal

thiosulfonylation (Scheme 2). A series of 1-bromoalkynes

(1a–p) employed for 1,2-thiosulfonylation with S-phenyl

benzenesulfonothioate (2a) to deliver the corresponding

(E)-1,2-thiosulfonylethenes 3(a–o)a in 37–79% yields with

excellent stereoselectivities. Notably, the nature and posi-

tion of the substituent(s) on the benzene ring had little in-

fluence on the outcome of the transformation (compare

3ba, 3da and 3ha). The reason behind the observed low se-

lectivity (E/Z = 10:1) of product 3ba was not clear; however,

it can be assumed that the strong electron-donating groups

(OMe) on the benzene ring might lead to a mixture of iso-

mers. Both 1- and 2-naphthyl-derived 1-bromoalkynes 1i

and 1j smoothly afforded the desired products 3ia and 3ja

C

A. H. Kumari et al.

Paper

Synthesis

in 69% and 67% yields, respectively. Interestingly, various

heteroaryl bearing alkynyl bromides 1k–n were well toler-

ated, leading to the expected products 3ka–na in good

yields and stereoselectivities. The structure and stereo-

chemistry of 3na were further established by single-crystal

X-ray analysis (see Figure 1 and the Supporting Informa-

tion).¹³Moreover, the alkyl-substituted 1-bromoalkynes 1o

and 1p were also reacted under the same conditions. Re-

markably, the corresponding vinyl thiosulfone 3oa was

smoothly obtained in 61% yield, whereas the product 3pa

was only formed in a trace amount.

the vicinal thiosulfonylation to deliver the anticipated (E)-

1,2-thiosulfonylethenes in satisfactory yields. Symmetrical

aryl and heteroaryl thiosulfonates 2b–f reacted with 1e

with no adverse effect on the outcome. Disappointingly, the

unsymmetrical thiosulfonates 2g–j significantly influenced

the stereoselectivity, albeit thiosulfonylated products 3eg,

3eh, 3ei and 3ej were obtained in satisfactory yields. To our

surprise, the 2-pyridyl-derived thiosulfonates 2k and 2l af-

forded the corresponding products 3ek and 3el in satisfac-

tory yields, predominantly as the E-isomers. Unfortunately,

S-benzyl thiosulfonate 2m was found to be unsuitable as a

substrate for this transformation. Next, (iodoethynyl)ben-

zene (1e′) was reacted with different thiosulfonates (2a,b,d)

to generate the corresponding products 3e′(a,b,d) in mod-

est yields. The less reactive (chloroethynyl)benzene (1e′′)

reacted sluggishly with 2a to form the desired product.

Encouraged by these results, we sought to evaluate the

scope of various thiosulfonates (2b–m) with (bro-

moethynyl)benzene (1e) (Scheme 3). Different symmetrical

and unsymmetrical thiosulfonates smoothly participated in

SO₂Ph

SO₂Ar

O

NiCl₂·6H₂O (5 mol%), Cs₂CO₃(3.0 equiv)

DMF, N₂, 90 °C, 3 h

O

S

Ph

NiCl₂·6H₂O (5 mol%), Cs₂CO₃(3.0 equiv)

DMF, N₂, 90 °C, 3 h

R

Br

+

Ph

S

R

X

+

Ar

S

1a–p

SPh

SR

2a

(E)-3(a–p)a

1e, 1e', 1e''

2b–m

(E)-3(e–e")b–m

SO₂Ph

1e: X = Br

SO₂Ph

SPh

F

Br

SO₂Ph

SPh

MeO

O

MeO

O

S

SPh

O

MeO

OMe

3ca: 69% (E/Z >30:1)

3da: 66% (E/Z >30:1)

3aa: 79% (E/Z >30:1)

S

3ba: 77% (E/Z 10:1)

S

SO₂Ph

Cl

SO₂Ph

F

Br

3ec: 58% (E/Z >30:1)

3eb: 64% (E/Z >30:1)

3ed: 54% (E/Z >30:1)

3ee: 62% (E/Z >30:1)

SPh

3fa: 71% (E/Z >30:1)

SO₂Ph

SPh

S

3ea: 75% (E/Z >30:1)

3ha: 62% (E/Z >30:1)

O

3ga: 65% (E/Z >30:1)

O

S

O

S

O

SO₂Ph

O

SO₂Ph

S

SPh

3ja:67% (E/Z >30:1)

SO₂Ph

O

SPh

S

SPh

3la: 37% (E/Z >30:1)

3ia: 69% (E/Z >30:1)

3ka: 62% (E/Z >30:1)

OMe

F

3ef: 52% (E/Z >30:1)

3eg: 68% (E/Z 5:1)

3eh: 57% (E/Z 6:1)

3ei: 54% (E/Z 4:1)

SO₂Ph

O

SPh

N

SPh

N

S

O

SPh

O

Ts

Boc

S

O

3pa: trace

3ma: 59% (E/Z >30:1)

3oa: 61% (E/Z >30:1)

3na: 53% (E/Z >30:1)

S

N

S

N

Scheme 2 Substrate scope for vicinal thiosulfonylation using 1a–p and

2a. All reactions were performed on a 0.5 mmol scale of 1a–p (1.0 equiv),

2a (1.5 equiv), NiCl₂·6H₂O (5 mol%) and Cs₂CO₃(3.0 equiv) in anhy-

drous DMF (2.5 mL) under N₂at 90 °C for 3 h. Isolated yields are given.

E/Z mixture ratios are based on ¹H NMR analysis.

OMe

3ej: 51% (E/Z 15:1)

3em: trace

3ek: 53% (E/Z >30:1)

3el: 51% (E/Z >30:1)

Ph

I (1e')

(1e'')

Cl

Ph

3e'a: 42% (E/Z >30:1)

3e'd: 26% (E/Z >30:1)

3e'b: 32% (E/Z >30:1)

3e"a: <10%

Scheme 3 Substrate scope for vicinal thiosulfonylation. All reactions

were performed on a 0.5 mmol scale of 1e, 1e′ or 1e′′ (1.0 equiv), 2a–m

(1.5 equiv), NiCl₂·6H₂O (5 mol%) and Cs₂CO₃(3.0 equiv) in anhydrous

DMF (2.5 mL) under N₂at 90 °C for 3 h. Isolated yields are given. E/Z

mixture ratios are based on ¹H NMR analysis.

Moreover, the scope of the vicinal thiosulfonylation re-

action could be extended to construct representative class-

es of thiosulfonylated products (Scheme 4). Several aryl-

and heteroaryl-derived alkynyl bromide substrates were

readily reacted with 2b to form the corresponding products

3(a–c,i,j,k,m,n)b in reasonably good yields. Similarly, the

heteroaryl-derived thiosulfonates 2f and 2k furnished thio-

sulfonylated products 3af, 3ak, 3kf and 3kl in acceptable

yields. Additionally, the naphthyl-containing thiosulfonates

2e and 2n gave the corresponding -heteroaryl-substituted

Figure 1 ORTEP representation of compound 3na (CCDC 2061705)

D

A. H. Kumari et al.

Paper

Synthesis

SO₂Ph

O

vinyl sulfones 3ke, 3ne and 3nn in moderate yields. It is

worth noting that these multifunctional vinyl (thio)sul-

fones are potentially valuable compounds in organic and

medical chemistry.¹⁴Interestingly, the thiophene-based vi-

nyl sulfones 3af and 3kf are promising structural scaffolds

in advanced functional materials.¹⁵

O

Ph

Br (1e)

SO₂Ph

S

Ph

+

Ph

Se

2o

standard conditions

SePh

4: 49%

3eo

not observed

Scheme 5 Synthesis of -keto selenosulfone 4 using 1e and 2o

SO₂Ar¹

O

Ar¹

NiCl₂·6H₂O (5 mol%)

S

Ar²

Ar /

HetAr

Ar /

HetAr

Br

+

S

SAr²

Cs₂CO₃(3.0 equiv), DMF

N₂, 90 °C

2b,e,f,k,l,n

1a,b,c,i,j,k,m,n

3(a,b,c,i,j,k,m,n)b,e,f,k,l,n

O

S

O

MeO

S

MeO

OMe

3ab: 72% (E/Z >30:1)

3bb: 63% (E/Z 5:1)

3cb: 67% (E/Z >30:1)

O

S

O

S

3ib: 59% (E/Z >30:1)

3kb: 55% (E/Z >30:1)

3jb: 58% (E/Z >30:1)

Figure 2 ORTEP representation of compound 4 (CCDC 2061706)

O

S

O

S

MeO

Next, the robustness of vicinal thiosulfonylation was

further examined by using dihaloalkene substrates 5a–h,

which were previously unexplored.^10cIndeed, the Cs₂CO₃-

mediated 1,2-thiosulfonylation afforded fruitful results

compared to the present Ni-catalyzed standard conditions

(Scheme 6). Thus, N-Ts/N-Boc-indole-derived dibro-

moalkenes 5a and 5b were studied and were found to

smoothly react with different thiosulfonates (2a,b,e,n) in

the presence of Cs₂CO₃(4 equiv) to deliver the expected

thiosulfones 3(m,n)a,b,e,n in good yields. Disappointingly,

N-Ms/N-Ns-indole-, 3-chloroquinoline- and imidazopyri-

dine-derived dibromoolefins 5c–f were either degraded or

reacted sluggishly under the same conditions (see the Sup-

porting Information). Similarly, dichloroalkene 5g and di-

fluoroalkene 5h were also challenging substrates for this

protocol.

To understand the generality of the vicinal difunctional-

ization, we turned our attention to more valuable sub-

strates 6a–e in order to install diverse substituents on the

products (Scheme 7). In this direction, we performed the

vicinal amidosulfonylation of 1a with N-phenylthio succin-

amide (6a) under the optimized conditions. Unfortunately,

we did not obtain the expected amido-sulfonylated prod-

uct; instead a 1,1-dithiolated-alkene was observed. Yang

and co-workers¹⁶had previously developed the synthesis of

1,1-dithio-1-alkenes using 1,1-dibromoalkenes with thiols

in the presence of DBU. It is worth mentioning that our pro-

tocol has the advantage of using bench-stable and odorless

sulfenylating reagents 6a and 6b instead of thiols. Using 2.5

equivalents of 6a, the yield of 7aa (85%) significantly

improved under similar conditions (Scheme 7). With fine-

S

N

Ts

S

N

S

Boc

S

3nb: 53% (E/Z >30:1)

3mb 51% (E/Z 12:1)

3af: 56% (E/Z 5:1)

S

O

S

O

MeO

S

N

3kf: 48% (E/Z >30:1)

3kl: 46% (E/Z >30:1)

3ak: 53% (E/Z 7:1)

O

S

O

S

O

S

N

S

N

Boc

3ke: 49% (E/Z >30:1)

3ne: 49% (E/Z >30:1)

3nn: 47% (E/Z >30:1)

Scheme 4 Substrate scope for vicinal thiosulfonylation. All reactions

were performed a 0.5 mmol scale of 1 (1.0 equiv), 2 (1.5 equiv),

NiCl₂·6H₂O (5 mol%) and Cs₂CO₃(3.0 equiv) in anhydrous DMF (2.5 mL)

under N₂at 90 °C for 3 h. Isolated yields are given. E/Z mixture ratios are

based on ¹H NMR analysis.

Moreover, the protocol was also extended to Se-phenyl

benzeneselenosulfonate (2o) under the optimized condi-

tions. As presented in Scheme 5, the reaction of 1e with 2o

did not afford the anticipated product 3eo. Instead, the un-

expected -keto selenosulfone 4 was obtained in 49% yield.

Further, the structure of 4 was ambiguously confirmed by

single-crystal X-ray analysis (Figure 2 and the Supporting

Information).¹³

E

A. H. Kumari et al.

Paper

Synthesis

O

Reactions were next carried out on gram scale under

the optimized conditions to highlight the efficacy of the

1,2-thiosulfonylation process. As shown in Scheme 8, reac-

tions of (bromoethynyl)benzene (1e) with S-aryl arylsul-

fonothioates 2a,b were performed on 5 mmol scale to pro-

duce 3ea in 68% (1.19 g) and 3eb in 57% (1.08 g) yields; thus

the protocol proved to be scalable with only a minor devia-

tion in the outcome. Developing a sequential one-pot oper-

ation offers attractive insights into a step-economic per-

spective, thereby avoiding the separation of intermedi-

ates.¹⁷Accordingly, a successive bromination with NBS

followed by vicinal thiosulfonylation of phenylacetylene

with 2a was performed on 10 mmol scale to give 3ea in 45%

(1.58 g) yield.

Ar

S

Br

S

O

Cs₂CO₃(4.0 equiv)

S

Ar

S

+

N

DMF, N₂, 90 °C, 4 h

N

2a,b,e,n

Ar

EWG

3(m–r)a,b,e,n

EWG = Ts (5a); Boc (5b)

Ms (5c); Ns (5d)

R

O

S

O

S

N

S

N

S

N

Ts

Boc

R

3ma (R = H): 57% (E/Z 25:1)

3ma: 46% (standard conditions)^a

3mb (R = Me): 49% (E/Z 25:1)

3na (R = H): 53% (E/Z >30:1)

3nb (R = Me): 45% (E/Z >30:1)

3nn: 43% (E/Z >30:1)

O

S

O

S

O

S

N

S

N

S

N

Boc

Ms

Ns

SO₂Ar

3ra: trace

O

3ne: 39% (E/Z >30:1)

3qa: not detected

standard conditions

S

Ar

Ph

Br

Ph

+

Unsuccessful substrates (5e–h)

Ar

S

SAr

5 mmol

1e (0.97 g)

Br

7.5 mmol

2a (1.87 g)/2b (2.08 g)

Br

MeO

Cl

F

3ea: 68% (1.19 g)

3eb: 57% (1.08 g)

N

Br

Cl

F

N

Cl

MeO

N

5f

Ph

SO₂Ph

sequential one-pot operation

(i) NBS (1.5 equiv), AgNO₃(10 mol%)

5g

5h

5e

H

Ph

10 mmol

(ii) PhSO₂SPh (2a, 3.75 g, 15 mmol)

standard conditions

Scheme 6 Substrate scope for vicinal thiosulfonylation. All reactions

were performed on a 0.5 mmol scale of 5 (1.0 equiv), 2 (1.5 equiv) and

Cs₂CO₃(4.0 equiv) in anhydrous DMF (2.5 mL) under N₂at 90 °C for 4 h.

Isolated yields are given. E/Z mixture ratios are based on ¹H NMR analy-

SPh

3ea

45% (1.58 g)

(1.17 g)

Scheme 8 Gram-scale vicinal thiosulfonylation reactions

a

sis. Reaction using NiCl₂·6H₂O (5 mol%). Ms: methanesulfonyl; Ns:

Control experiments were performed on the 1,2-thio-

sulfonylation under the standard conditions to gain insights

into the reaction mechanism (Scheme 9). The reaction of 2a

with phenylacetylene gave the desired product 3ea in <10%

yield (Scheme 9, a). In contrast, the reaction of 2a with 3-

phenylpropiolic acid (8) formed alkynyl thioether 9,¹⁸

whilst the use of TMS-derived phenylacetylene 10 afforded

a mixture of products along with 9 (Schemes 9, b and c).

Additionally, thioalkyne 9 failed to react with 2a under the

same conditions (Scheme 9, d). Moreover, the standard re-

action was performed in the presence of radical scavengers.

Using BHT (4 equiv), the desired product 3ea was formed in

only 14% yield (Scheme 9, e). Furthermore, the reaction was

almost totally inhibited in the presence of TEMPO (4 equiv),

nosyl (4-O₂NC₆H₄SO₂).

tuned reaction conditions in hand, we probed the scope of

1-bromoalkynes 1a,e,g,j,k,l and N-arylthio succinimides 6a

and 6b to provide the corresponding 1,1-dithioalkenes

7(a,e,g,k)a,b, 7ja and 7lb in 69–88% yields. However, the cy-

clopropyl-derived 1,1-dithio-1-alkene 7pb was detected in

only a trace amount. This protocol was also applied to other

sulfenylating agents (6c–e) under the same conditions but

failed to give the desired products.

O

NiCl₂·6H₂O (5 mol%)

Cs₂CO₃(3.0 equiv)

S

R

Ar /

HetAr

N

Ar /

HetAr

Br

+

S

DMF, 90 °C, 2 h

R

O

6a (R = H)

6b (R = Me)

1a,e,g,j,k,l

R

7(a,e,g,j,k,l)a,b

O

standard conditions

S

MeO

S

R

+

3ea: <10%

(a)

(b)

(c)

R

Ph

H

R

S

Ph

S

2a (1.5 equiv)

O

Ph

CO₂H

TMS

R

Ph

SPh

R

7aa (R = H): 85%

7ab (R = Me): 88%

S

Ph

7ga (R = H): 76%

7gb (R = Me): 79%

7ea (R = H): 86%

7eb (R = Me): 80%

Ph

S

8

10

9

2a (1.5 equiv)

9

O

S

R

9 + mixture

Ph

S

Ph

S

2a (1.5 equiv)

O

S

O

standard conditions

R

+

no reaction

(d)

(e)

SPh

Br

S

Ph

7ja: 81%

7ka (R = H): 71%

7kb (R = Me): 75%

Ph

S

7lb: 69%

2a (1.5 equiv)

S

PhO₂S

Unsuccessful substrates (6c–e)

O

standard conditions

O

Ph

O

S

Ph

with BHT (4 equiv)

S

EtO

S

Ph

S

Ph

SPh

Ph

S

P

Ph

S

7pb: traces

1e

2a (1.5 equiv)

3ea (14%)

6d

6c

6e

PhO₂S

O

standard conditions

+

(f)

Ph

Br

S

Ph

Scheme 7 Substrate scope for the 1,1-dithiolation of 1 with N-arylthio

succinamides 6a and 6b. All reactions were performed on a 0.5 mmol

scale of 1 (1.0 equiv), 6a,b (2.5 equiv), NiCl₂·6H₂O (5 mol%) and Cs₂CO₃

(3.0 equiv) in anhydrous DMF (2.5 mL) under N₂at 90 °C for 2 h. Isolat-

ed yields are given.

with TEMPO (4 equiv)

Ph

S

Ph

SPh

3ea (trace)

1e

2a (1.5 equiv)

Scheme 9 Control experiments

F

A. H. Kumari et al.

Paper

Synthesis

with only a trace amount of 3ea being detected (Scheme 9,

f). Overall, these results indicate that the thiosulfonylation

process possibly involves a radical pathway.

cinimides to furnish 1,1-dithio-1-alkenes in high yields. The

protocol is also amenable to large-scale synthesis, which is

quite challenging when using other thiosulfonylation meth-

ods. A step-economic, sequential one-pot bromination and

thiosulfonylation approach has been achieved on gram

scale, which offers an additional benefit to the described

process. Finally, a plausible mechanism has been presented

to rationalize the experimental outcome.

Based on the above results and literature precedent,^10,19–

²¹a plausible mechanism has been proposed for this trans-

formation (Scheme 10). The thermal homolytic cleavage of

thiosulfonate 2a can generate a thiyl radical¹⁹and a sulfonyl

radical species (Scheme 10, a).²⁰Firstly, Ni(II) is reduced to

Ni(0), which can react with 1e to form the alkynyl-Ni spe-

cies A.^2aThe sulfenyl radical would react with A to form

transient alkenyl radical B,^10dwhich can then react with the

sulfonyl radical to give intermediate C. Alternately, the radi-

cal B can undergo oxidation with the sulfonyl radical to

generate alkenyl cation D and a sulfonyl anion. Reaction

with the sulfonyl anion subsequently produces intermedi-

ate C. Finally, hydrogen may be abstracted from DMF²¹to

produce the desired product 3ea and the Ni catalyst is re-

generated to continue the catalytic process. Additionally,

the transition-state model E can explain the steric repulsion

between the sulfone and the thioether, which may form the

Z-isomer as a minor product. The mechanism for the for-

mation of 1,1-dithioalkenes 7 is still not clear.¹⁶However, a

tentative mechanism has been proposed in the Supporting

Information based on experimental results.

All reagents were purchased from Sigma-Aldrich, TCI, Alfa Aesar, SD-

Fine, SRL, Spectrochem and AVRA chemicals, and were used without

further purification unless otherwise stated. Solvents were dried over

activated 4 Å molecular sieves for all reactions carried out under an

inert atmosphere. The progress of reactions was monitored by thin-

layer chromatography (TLC) using Silica gel 60 F254 plates. Visualiza-

tion of samples was achieved by a combination of ultraviolet light

(254 nm) and staining with potassium permanganate solution, iodine

or p-anisaldehyde. Flash column chromatography was performed us-

ing SRL silica gel (100–200 mesh) as the stationary phase. Melting

points were measured in open capillaries using a DBK digital melting

point apparatus and are uncorrected. ¹H and ¹³C NMR spectra were

recorded using a Bruker AVIII 400 spectrometer (¹H: 400 MHz; ¹³C:

101 MHz) at 300 K. Chemical shifts () are given in ppm relative to

TMS and the coupling constants (J) are quoted in Hz. For spectra re-

corded in CDCl₃, the signals at  7.26 (due to residual CHCl₃) and at 

77.16 (the resonance of CDCl₃) were used as internal references. ¹H

NMR spectral data are reported as follows: chemical shift (multiplici-

ty, coupling constant, integration). The following abbreviations are

used for multiplicities: s (singlet), d (doublet), t (triplet), q (quartet),

dd (doublet of doublets), td (triplet of doublets), quin (quintet), sept

(septet), m (multiplet). All NMR spectra were processed using

MestReNova version 6.0.2(v). High-resolution mass spectrometry

(HRMS) was performed using a Thermo scientific ExactiveTM Or-

bitrap mass spectrometer or Q STAR XL Hybrid MS/MS spectrometer

by employing ESI-TOF techniques. Spectra were obtained using a

lock-mass to adjust the calibrated mass scale.

homolytic cleavage

PhSO₂-SPh (2a)

(a)

+

PhSO₂

PhS

heat, Cs₂CO₃

Ni(II)

Cs₂CO₃

SO₂Ph

Ph

Ni(0)

O

Ph

Br

SPh

1e

A

3ea

Cs₂CO₃

Br

DMF

Br

NMe₂

Br

Ph

Ni[II]

Br

PhO₂S

Ph

[II]Ni

Ni[II]

Ph

S

D

C

S

Ph

PhSO₂

Ph

2a

PhSO₂

disfavored

XRD experiments were performed by measuring the X-ray intensity

data on a Bruker SMART APEX III single-crystal X-ray CCD diffractom-

eter using graphite-monochromated radiation (Mo-K = 0.71073) at

low temperature (100 K). The X-ray generator was operated at 50 kV

and 30 mA. A preliminary set of cell constants and an orientation ma-

trix were calculated from a total of 36 frames. The optimized strategy

used for data collection consisted of different sets of ϕ and  scans

with 0.5° steps ϕ/. Data were collected with a timeframe of 10 sec-

onds for all the components by keeping the sample-to-detector dis-

tance fixed at 40 cm. All the data are corrected for Lorentzian, polar-

ization and absorption effects using SAINT and SADABS (Bruker,

2016). SHELX-97 was used for structure solution and full-matrix

least-squares refinement on F2 with anisotropic displacement pa-

rameters for non-H atoms. Hydrogen atoms associated with carbon

atoms were fixed in geometrically constrained positions. The hydro-

gen atoms associated with oxygen and nitrogen atoms were included

in the located positions. ORTEP diagrams were generated by using the

X-Seed software package (version 2.0).

Br

PhSO₂

Ph

Ni[II]

Ph

Br

[II]Ni

Ph

S

PhSO₂

Ph

S

Ph

E

B

(not obsereved)

Ph

Scheme 10 A plausible mechanism for the vicinal thiosulfonylation

In summary, we have successfully demonstrated the Ni-

catalyzed vicinal thiosulfonylation of alkynyl bromides

with thiosulfonates in the presence of Cs₂CO₃under mild

reaction conditions. The atom transfer radical addition

(ATRA) protocol has been utilized to efficiently generate a

series of (E)-1,2-thiosulfonylethenes in good to high yields

and with high levels of stereoselectivity. Substantial varia-

tion of both the alkynyl bromides and thiosulfonates

demonstrates the broad functional group tolerance and

compatibility of the process. Indole-derived 1,1-bro-

moalkenes have also been employed as valuable substrates

for the stereoselective synthesis of vinyl thiosulfones. In ad-

dition, the methodology has been further extended to the

1,1-dithiolation of alkynyl bromides with N-arylthio suc-

(E)-1,2-Thiosulfonylethenes; General Procedure 1 (GP1)

A heat-gun-dried Schlenk tube was charged with alkynyl bromide

1a–p (0.5 mmol, 1.0 equiv), thiosulfonate 2a–o (0.75 mmol, 1.5

equiv), NiCl₂·6H₂O (5.9 mg, 0.025 mmol, 0.05 equiv) and Cs₂CO₃(1.5

G

A. H. Kumari et al.

Paper

Synthesis

mmol, 3.0 equiv) in DMF (2.5 mL). The reaction mixture was stirred at

90 °C for 3 h under N₂. The progress was monitored by TLC (until the

reaction appeared to be complete or was not proceeding any further).

The mixture was quenched by the addition of H₂O (10 mL) followed

by extraction with EtOAc (3 × 10 mL). The combined organic layers

were washed with brine (2 × 10 mL), dried over anhydrous Na₂SO₄,

and the solvent was removed under reduced pressure. The resulting

residue was subjected to flash chromatography (silica gel, 100–200

mesh, eluting with 8% to 10% EtOAc/PE) to afford the corresponding

(E)-1,2-thiosulfonylethene.

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3da as a yellow

viscous liquid (126.2 mg, 66%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 8.14 (s, 1 H), 7.66 (dd, J = 8.4, 1.2 Hz, 2 H),

7.53 (tt, J = 7.4, 1.2 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.43–7.37 (m, 5 H), 7.22

(d, J = 8.0 Hz, 1 H), 6.92–6.89 (m, 1 H), 6.78–6.74 (m, 2 H), 3.73 (s, 3 H).

These data are consistent with literature values.^10c

(E)-Phenyl[2-phenyl-2-(phenylsulfonyl)vinyl]sulfane (3ea)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75 mmol),

NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for

3 h. Purification by flash column chromatography (silica gel, 8%

EtOAc/PE) yielded the title compound 3ea as a colorless solid (132.0

mg, 75%, >30:1 mixture of E/Z isomers).

(E)-[2-(3,4-Dimethoxyphenyl)-2-(phenylsulfonyl)vinyl]-

(phenyl)sulfane (3aa)

Following GP1 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3aa as a colorless

solid (162.9 mg, 79%, >30:1 mixture of E/Z isomers).

Mp 91–93 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.15 (s, 1 H), 7.63 (dd, J = 8.3, 1.1 Hz, 2

H), 7.53 (t, J = 7.4 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.42–7.33 (m, 8 H), 7.21

(dd, J = 7.9, 1.6 Hz, 2 H).

Mp 94–96 °C.

¹³C NMR (101 MHz, CDCl₃):  = 144.2, 139.4, 136.1, 133.2, 132.9, 131.3

(2 C), 130.7, 130.3 (2 C), 129.7 (2 C), 129.6, 128.9, 128.8 (3 C), 128.3.

These data are consistent with literature values.^10c

¹H NMR (400 MHz, CDCl₃):  = 8.11 (s, 1 H), 7.64 (dd, J = 8.4, 1.2 Hz, 2

H), 7.53 (tt, J = 7.4, 1.2 Hz, 1 H), 7.50–7.47 (m, 2 H), 7.43–7.37 (m, 5 H),

6.81 (d, J = 8.2 Hz, 1 H), 6.77–6.73 (m, 2 H), 3.88 (s, 3 H), 3.78 (s, 3 H).

These data are consistent with literature values.^10c

(E)-Phenyl[2-(phenylsulfonyl)-2-(p-tolyl)vinyl]sulfane (3fa)

(E)-Phenyl[2-(phenylsulfonyl)-2-(3,4,5-trimethoxyphenyl)-

vinyl]sulfane (3ba)

Following GP1 using 1-(bromoethynyl)-4-methylbenzene (1f) (97.5

mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3fa as a colorless solid

(130.1 mg, 71%, >30:1 mixture of E/Z isomers).

Following GP1 using 5-(bromoethynyl)-1,2,3-trimethoxybenzene

(1b) (135.5 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a)

(187.5 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3ba as a

colorless solid (170.4 mg, 77%, >10:1 mixture of E/Z isomers).

Mp 135–137 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.11 (s, 1 H), 7.63 (dd, J = 8.4, 1.2 Hz, 2

H), 7.53 (tt, J = 7.4, 1.2 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.43–7.36 (m, 5 H),

7.14 (d, J = 8.0 Hz, 2 H), 7.09 (d, J = 8.2 Hz, 2 H), 2.35 (s, 3 H).

Mp 142–144 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.11 (s, 1 H), 7.68 (d, J = 7.6 Hz, 2 H),

7.54 (t, J = 7.5 Hz, 1 H), 7.48 (d, J = 6.0 Hz, 2 H), 7.45–7.37 (m, 5 H),

6.38 (s, 2 H), 3.85 (s, 3 H), 3.72 (s, 6 H).

These data are consistent with literature values.^10c

(E)-[2-(4-Isopropylphenyl)-2-(phenylsulfonyl)vinyl](phenyl)-

sulfane (3ga)

(E)-[2-(4-Methoxyphenyl)-2-(phenylsulfonyl)vinyl](phenyl)-

sulfane (3ca)

Following GP1 using 1-(bromoethynyl)-4-isopropylbenzene (1g)

(111.5 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3ga as a color-

less solid (128.2 mg, 65%, >30:1 mixture of E/Z isomers).

Following GP1 using 1-(bromoethynyl)-4-methoxybenzene (1c)

(105.0 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3ca as a colorless

solid (132.0 mg, 69%, >30:1 mixture of E/Z isomers).

Mp 140–142 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.12 (s, 1 H), 7.63 (dd, J = 8.4, 1.2 Hz, 2

H), 7.54 (tt, J = 7.4, 1.2 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.42–7.36 (m, 5 H),

7.19 (d, J = 8.2 Hz, 2 H), 7.12 (d, J = 8.3 Hz, 2 H), 2.89 (sept, J = 6.9 Hz, 1

H), 1.24 (d, J = 6.9 Hz, 6 H).

¹³C NMR (101 MHz, CDCl₃):  = 150.3, 143.9, 139.6, 136.2, 133.1,

133.0, 131.3 (2 C), 130.1 (2 C), 129.7 (2 C), 128.9 (2 C), 128.7, 128.3 (2

C), 127.9, 126.9 (2 C), 34.0, 23.9 (2 C).

Mp 96–97 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.14 (s, 1 H), 7.65 (dd, J = 8.4, 1.2 Hz, 2 H),

7.53 (tt, J = 7.4, 1.2 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.43–7.37 (m, 5 H), 7.24

(t, J = 7.9 Hz, 1 H), 6.92–6.88 (m, 1 H), 6.78–6.75 (m, 2 H), 3.74 (s, 3 H).

These data are consistent with literature values.^10c

(E)-[2-(3-Methoxyphenyl)-2-(phenylsulfonyl)vinyl](phenyl)-

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₃H₂₃O₂S₂: 395.1139; found:

sulfane (3da)

395.1140.

Following GP1 using 1-(bromoethynyl)-3-methoxybenzene (1d)

(105.5 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

H

A. H. Kumari et al.

Paper

Synthesis

(E)-[2-(2-Chlorophenyl)-2-(phenylsulfonyl)vinyl](phenyl)sulfane

(E)-2-(1-(Phenylsulfonyl)-2-(phenylthio)vinyl)furan (3la)

(3ha)

Following GP1 using 2-(bromoethynyl)furan (1l) (85.4 mg, 0.5 mmol),

S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75 mmol),

NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for

3 h. Purification by flash column chromatography (silica gel, 10%

EtOAc/PE) yielded the title compound 3la as a colorless solid (63.3 mg,

37%, >30:1 mixture of E/Z isomers).

Following GP1 using 1-(bromoethynyl)-2-chlorobenzene (1h) (107.7

mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3ha as a colorless solid

(119.9 mg, 62%, >30:1 mixture of E/Z isomers).

Mp 101–103°C.

Mp 100–102 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.07 (s, 1 H), 7.87 (d, J = 7.3 Hz, 2 H),

7.60–7.52 (m, 3 H), 7.50–7.38 (m, 6 H), 6.83 (d, J = 3.5 Hz, 1 H), 6.43

(dd, J = 3.5, 1.8 Hz, 1 H).

¹H NMR (400 MHz, CDCl₃):  = 8.19 (s, 1 H), 7.60 (d, J = 8.5 Hz, 2 H),

7.56 (tt, J = 7.4, 1.2 Hz, 1 H), 7.49–7.46 (m, 2 H), 7.42 (d, J = 7.7 Hz, 2

H), 7.39–7.36 (m, 5 H), 7.33–7.31 (m, 2 H).

¹³C NMR (101 MHz, CDCl₃):  = 146.0, 138.9, 134.9, 133.4, 133.2,

132.9, 132.5, 131.4 (2 C), 131.1, 129.8, 129.7 (2 C), 129.1, 129.0 (2 C),

128.9, 128.7 (2 C), 127.1.

These data are consistent with literature values.^10c

(E)-2-[1-(Phenylsulfonyl)-2-(phenylthio)vinyl]-1-tosyl-1H-indole

(3ma)

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₀H₁₅ClNaO₂S₂: 409.0100;

found: 409.0095.

Following GP1 using 2-(bromoethynyl)-1-tosyl-1H-indole (1m)

(187.1 mg, 0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3ma as a color-

less solid (161.0 mg, 59%, >30:1 mixture of E/Z isomers).

(E)-[2-(Naphthalen-1-yl)-2-(phenylsulfonyl)vinyl](phenyl)sulfane

(3ia)

Following GP1 using 1-(bromoethynyl)naphthalene (1i) (115.5 mg,

0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3ia as a colorless solid

(138.9 mg, 69%, >30:1 mixture of E/Z isomers).

Mp 140–142 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.30 (s, 1 H), 7.95 (d, J = 8.4 Hz, 1 H),

7.74 (d, J = 8.4 Hz, 2 H), 7.54 (s, 1 H), 7.52 (dd, J = 8.4, 1.2 Hz, 2 H),

7.47–7.42 (m, 3 H), 7.39 (dd, J = 5.1, 2.0 Hz, 2 H), 7.31–7.26 (m, 3 H),

7.24 (m, 3 H), 7.25–7.21 (d, J = 7.4 Hz, 1 H), 7.14 (t, J = 7.9 Hz, 1 H),

2.38 (s, 3 H).

Mp 69–71 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.31 (s, 1 H), 7.79 (d, J = 8.2 Hz, 1 H),

7.73 (d, J = 8.1 Hz, 1 H), 7.47 (d, J = 7.5 Hz, 2 H), 7.42 (d, J = 8.4 Hz, 1 H),

7.35–7.31 (m, 5 H), 7.27–7.19 (m, 6 H), 7.12 (d, J = 6.9 Hz, 1 H).

¹³C NMR (101 MHz, CDCl₃):  = 146.6, 145.4, 139.1, 135.1, 134.7,

133.3, 132.5, 131.4 (2 C), 130.1 (2 C), 129.8 (2 C), 129.0, 128.9 (2 C),

128.5, 128.2 (2 C), 128.1, 127.8, 127.1 (2 C), 125.3, 123.6, 120.7, 113.8,

112.0, 21.8.

These data are consistent with literature values.^10c

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₉H₂₄NO₄S₃: 546.0867;

found: 546.0863.

(E)-[2-(Naphthalen-2-yl)-2-(phenylsulfonyl)vinyl](phenyl)sulfane

(3ja)

(E)-tert-Butyl 2-[1-(Phenylsulfonyl)-2-(phenylthio)vinyl]-1H-

indole-1-carboxylate (3na)

Following GP1 using 2-(bromoethynyl)naphthalene (1j) (173.3 mg,

0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3ja as a yellow liquid

(134.8 mg, 67%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 8.22 (s, 1 H), 7.84–7.77 (m, 3 H), 7.73

(s, 1 H), 7.64 (d, J = 7.4 Hz, 2 H), 7.53–7.48 (m, 5 H), 7.41–7.34 (m, 5

H), 7.30 (dd, J = 8.5, 1.5 Hz, 1 H).

Following GP1 using tert-butyl 2-(bromoethynyl)-1H-indole-1-car-

boxylate (1n) (160.1 mg, 0.5 mmol), S-phenyl benzenesulfonothioate

(2a) (187.5 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and

Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column

chromatography (silica gel, 10% EtOAc/PE) yielded the title compound

3na as a brown solid (130.3 mg, 53%, >30:1 mixture of E/Z isomers).

Mp 115–117 °C.

These data are consistent with literature values.^10c

¹H NMR (400 MHz, CDCl₃):  = 8.32 (s, 1 H), 7.70 (d, J = 8.5 Hz, 2 H),

7.58 (s, 1 H), 7.49–7.45 (m, 3 H), 7.41–7.33 (m, 6 H), 7.31–7.26 (m, 1

H), 7.13–7.05 (m, 2 H), 1.67 (s, 9 H).

(E)-2-[1-(Phenylsulfonyl)-2-(phenylthio)vinyl]thiophene (3ka)

¹³C NMR (101 MHz, CDCl₃):  = 149.3, 146.2, 139.5, 135.1, 133.2,

132.7, 131.3 (2 C), 129.7 (2 C), 129.0 (2 C), 128.8, 128.2 (2 C), 127.9,

127.7, 127.3, 124.9, 122.9, 120.0, 115.4, 110.0, 84.6, 28.3 (3 C).

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₇H₂₅NNaO₄S₂: 514.1123;

found: 514.1117.

Following GP1 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75 mmol),

NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for

3 h. Purification by flash column chromatography (silica gel, 10%

EtOAc/PE) yielded the title compound 3ka as a light yellow solid

(111.1 mg, 62%, >30:1 mixture of E/Z isomers).

Mp 99–100 °C.

(E)-Phenyl[4-phenyl-2-(phenylsulfonyl)but-1-en-1-yl]sulfane

¹H NMR (400 MHz, CDCl₃):  = 8.20 (s, 1 H), 7.74 (d, J = 7.2 Hz, 2 H),

7.55–7.50 (m, 3 H), 7.45–7.40 (m, 6 H), 7.20 (dd, J = 3.7, 1.2 Hz, 1 H),

7.04–7.02 (m, 1 H).

(3oa)

Following GP1 using (4-bromobut-3-yn-1-yl)benzene (1o) (104.9 mg,

0.5 mmol), S-phenyl benzenesulfonothioate (2a) (187.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

These data are consistent with literature values.^10c

I

A. H. Kumari et al.

Paper

Synthesis

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3oa as a colorless liquid

(116.0 mg, 61%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 8.10–8.04 (m, 2 H), 7.67 (tt, J = 7.4, 1.2

Hz, 1 H), 7.58 (t, J = 7.6 Hz, 2 H), 7.32–7.28 (m, 3 H), 7.26–7.20 (m, 3

H), 7.19–7.16 (m, 2 H), 7.01 (d, J = 6.6 Hz, 2 H), 6.66 (s, 1 H), 2.77 (t, J =

7.3 Hz, 2 H), 2.63 (t, J = 7.4 Hz, 2 H).

¹³C NMR (101 MHz, CDCl₃):  = 143.0, 140.9, 140.1, 135.9, 133.8,

132.2, 131.0 (2 C), 129.4 (2 C), 129.3 (2 C), 128.9 (2 C), 128.6 (2 C),

128.3, 127.6 (2 C), 126.3, 35.2, 34.4.

¹H NMR (400 MHz, CDCl₃):  = 8.04 (s, 1 H), 7.54–7.50 (m, 4 H), 7.44

(d, J = 8.7 Hz, 2 H), 7.39–7.31 (m, 5 H), 7.20 (dd, J = 7.9, 1.5 Hz, 2 H).

¹³C NMR (101 MHz, CDCl₃):  = 143.7, 138.3, 136.3, 132.9 (2 C), 132.8

(2 C), 132.3 (2 C), 131.8, 130.3 (2 C), 130.2, 129.9, 129.8 (2 C), 129.0 (2

C), 128.6, 123.3.

HRMS (ESI-TOF): m/z [M + K]⁺calcd for C₂₀H₁₄Br₂KO₂S₂: 546.8439;

found: 546.8433.

(E)-Naphthalen-2-yl[2-(naphthalen-2-ylsulfonyl)-2-phenyl-

vinyl]sulfane (3ee)

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₂H₂₀NaO₂S₂: 403.0802;

found: 403.0797.

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-naphthalen-1-yl naphthalene-1-sulfonothioate (2e) (175.2

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3ee as a yellow

solid (140.3 mg, 62%, >30:1 mixture of E/Z isomers).

(E)-(2-Phenyl-2-tosylvinyl)(p-tolyl)sulfane (3eb)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b) (208.8 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3eb as a colorless

solid (121.8 mg, 64%, >30:1 mixture of E/Z isomers).

Mp 150–152 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.31 (s, 1 H), 8.20 (s, 1 H), 7.98 (s, 1 H),

7.89–7.82 (m, 6 H), 7.65–7.59 (m, 2 H), 7.58–7.54 (m, 4 H), 7.37–7.30

(m, 3 H), 7.24 (dd, J = 8.1, 1.6 Hz, 2 H).

Mp 178–180 °C.

¹³C NMR (101 MHz, CDCl₃):  = 144.3, 136.33, 136.31, 135.1, 133.7,

132.9, 132.1, 130.7, 130.5, 130.4 (2 C), 130.03, 130.00, 129.65, 129.62,

129.5, 129.22, 129.16, 128.9 (2 C), 128.1, 128.02, 127.99, 127.8, 127.6,

127.3, 127.2, 123.2.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₂₈H₂₄NO₂S₂: 470.1248;

found: 470.1248.

¹H NMR (400 MHz, CDCl₃):  = 8.07 (s, 1 H), 7.49 (d, J = 8.2 Hz, 2 H),

7.37–7.33 (m, 5 H), 7.22–7.17 (m, 6 H), 2.38 (s, 3 H), 2.37 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 144.5, 144.0, 139.1, 136.5, 135.8, 131.6

(2 C), 130.9, 130.42 (2 C), 130.35 (2 C), 129.6 (2 C), 129.43, 129.38,

128.7 (2 C), 128.3 (2 C), 21.7, 21.3.

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₂H₂₀NaO₂S₂: 403.0802;

found: 403.0797.

(E)-2-{[2-Phenyl-2-(thiophen-2-ylsulfonyl)vinyl]thio}thiophene

(3ef)

These data are consistent with literature values.^10d

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-thiophen-2-yl thiophene-2-sulfonothioate (2f) (131.2 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3ef as a yellow solid

(94.7 mg, 52%, >30:1 mixture of E/Z isomers).

(E)-(4-Fluorophenyl){2-[(4-fluorophenyl)sulfonyl]-2-phenyl-

vinyl}sulfane (3ec)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-(4-fluorophenyl) 4-fluorobenzenesulfonothioate (2c)

(143.1 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3ec as a

colorless solid (112.6 mg, 58%, >30:1 mixture of E/Z isomers).

Mp 116–118 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.92 (s, 1 H), 7.59 (dd, J = 5.0, 1.3 Hz, 1

H), 7.47 (dd, J = 5.4, 1.2 Hz, 1 H), 7.41–7.36 (m, 3 H), 7.32 (dd, J = 3.8,

1.3 Hz, 1 H), 7.29–7.26 (m, 2 H), 7.25 (dd, J = 3.6, 1.2 Hz, 1 H), 7.06–

7.03 (m, 1 H), 6.99 (dd, J = 4.9, 3.8 Hz, 1 H).

¹³C NMR (101 MHz, CDCl₃):  = 145.5, 140.3, 136.1, 135.4, 134.4,

134.1, 131.4, 130.3 (2 C), 130.1, 129.9, 129.2, 128.9 (2 C), 128.2, 127.6.

Mp 98–100 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.01 (s, 1 H), 7.63–7.58 (m, 2 H), 7.48–

7.44 (m, 2 H), 7.39–7.33 (m, 3 H), 7.20 (dd, J = 7.9, 1.6 Hz, 2 H), 7.12–

7.04 (m, 4 H).

¹³C NMR (101 MHz, CDCl₃):  = 165.5 (d, J = 255.9 Hz), 163.4 (d, J =

264.1 Hz), 144.5, 136.0, 135.3 (d, J = 3.2 Hz), 134.0 (d, J = 8.5 Hz, 2 C),

131.1 (d, J = 9.5 Hz, 2 C), 130.3 (d, J = 6.3 Hz, 3 C), 129.8 (2 C), 128.9 (3

C), 127.8 (d, J = 3.5 Hz), 116.99 (d, J = 22.2 Hz), 116.26 (d, J = 22.6 Hz).

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₁₆H₁₂NaO₂S₄: 386.9618;

found: 386.9613.

(E)-Phenyl(2-phenyl-2-tosylvinyl)sulfane (3eg)

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₀H₁₄F₂NaO₂S₂: 411.0301;

found: 411.0295.

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-phenyl 4-methylbenzenesulfonothioate (2g) (198.3 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3eg as a colorless

solid (124.6 mg, 68%, >5:1 mixture of E/Z isomers).

(E)-(4-Bromophenyl){2-[(4-bromophenyl)sulfonyl)]-2-phenyl-

vinyl}sulfane (3ed)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-(4-bromophenyl) 4-bromobenzenesulfonothioate (2d)

(306.1 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3ed as a

colorless solid (137.7 mg, 54%, >30:1 mixture of E/Z isomers).

Mp 118–120 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.11 (s, 1 H), 7.52–7.45 (m, 4 H), 7.39–

7.34 (m, 6 H), 7.23–7.18 (m, 4 H), 2.38 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 144.1, 143.6, 136.4, 132.9, 131.6, 131.2

(2 C), 130.8, 130.3 (2 C), 129.7 (2 C), 129.6 (2 C), 129.5, 128.9, 128.7 (2

C), 128.3 (2 C), 21.7.

Mp 188–190 °C.

J

A. H. Kumari et al.

Paper

Synthesis

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₂₁H₂₂NO₂S₂: 384.1092;

(E)-2-{[2-Phenyl-2-(phenylsulfonyl)vinyl]thio}pyridine (3ek)

found: 384.1087.

These data are consistent with literature values.^10d

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-pyridin-2-yl benzenesulfonothioate (2k) (188.5 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 10% EtOAc/PE) yielded the title compound 3ek as a yellow liquid

(93.6 mg, 53%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 9.14 (s, 1 H), 8.61–8.58 (m, 1 H), 7.67

(dd, J = 8.4, 1.2 Hz, 2 H), 7.58 (td, J = 7.9, 1.8 Hz, 1 H), 7.52 (tt, J = 7.4,

1.2 Hz, 1 H), 7.42–7.32 (m, 5 H), 7.19–7.14 (m, 4 H).

¹³C NMR (101 MHz, CDCl₃):  = 153.4, 150.3, 139.4, 138.9, 137.1,

136.7, 133.2, 131.4, 130.2 (2 C), 129.5, 128.9 (2 C), 128.8 (2 C), 128.4

(2 C), 123.1, 121.8.

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₁₉H₁₅NNaO₂S₂: 376.0442;

found: 376.0437.

(E)-(4-Methoxyphenyl)(2-phenyl-2-tosylvinyl)sulfane (3eh)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-(4-methoxyphenyl)-4-methylbenzenesulfonothioate (2h)

(220.8 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3eh as a

colorless solid (113.0 mg, 57%, >6:1 mixture of E/Z isomers).

Mp 175–172 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.00 (s, 1 H), 7.48 (d, J = 8.3 Hz, 2 H),

7.41 (d, J = 8.9 Hz, 2 H), 7.36–7.31 (m, 3 H), 7.22–7.17 (m, 4 H), 6.91

(d, J = 8.9 Hz, 2 H), 3.83 (s, 3 H), 2.38 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 160.5, 145.5, 144.0, 136.6, 135.3, 134.0

(2 C), 132.8, 130.9, 130.4 (2 C), 129.6, 129.4, 128.7, 128.3 (2 C), 123.3,

115.3 (2 C), 114.7, 55.7, 21.7.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₂₂H₂₄NO₃S₂: 414.1198;

found: 414.1195.

(E)-2-[(2-Phenyl-1-tosylvinyl)thio]pyridine (3el)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-pyridin-2-yl 4-methylbenzenesulfonothioate (2l) (199.0

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3el as a colorless

liquid (93.7 mg, 51%, >30:1 mixture of E/Z isomers).

These data are consistent with literature values.^10d

(E)-(4-Fluorophenyl)[2-phenyl-2-(phenylsulfonyl)vinyl]sulfane

(3ei)

¹H NMR (400 MHz, CDCl₃):  = 9.10 (s, 1 H), 8.60–6.58 (m, 1 H), 7.59

(dd, J = 7.5, 1.9 Hz, 1 H), 7.56–7.52 (m, 2 H), 7.37–7.31 (m, 3 H), 7.20–

7.15 (m, 6 H), 2.38 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 153.6, 150.3, 144.1, 138.3, 137.1,

137.0, 136.5, 131.6, 130.3 (2 C), 129.6 (2 C), 129.5, 128.8 (2 C), 128.5

(2 C), 123.1, 121.8, 21.8.

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₀H₁₈NO₂S₂: 368.0773;

found: 368.0767.

These data are consistent with literature values.^10d

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-(4-fluorophenyl) benzenesulfonothioate (2i) (201.2 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3ei as a yellow solid

(100.0 mg, 54%, >30:1 mixture of E/Z isomers).

Mp 115–117 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.02 (s, 1 H), 7.61 (d, J = 9.3 Hz, 2 H),

7.53 (t, J = 7.5 Hz, 1 H), 7.48–7.44 (m, 2 H), 7.42–7.31 (m, 5 H), 7.21–

7.17 (m, 2 H), 7.11–7.06 (m, 2 H).

(E)-[2-(3,4-Dimethoxyphenyl)-2-tosylvinyl](p-tolyl)sulfane (3ab)

Following GP1 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b)

(208.8 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3ab as a

white solid (158.6 mg, 72%, >30:1 mixture of E/Z isomers).

¹³C NMR (101 MHz, CDCl₃):  = 163.2 (d, J = 250.0 Hz), 144.4 (d, J =

20.8 Hz), 139.2, 136.2, 134.05 (d, J = 4.5 Hz), 133.96 (d, J = 4.4 Hz),

131.1 (d, J = 9.5 Hz), 130.5, 130.3 (2 C), 129.8, 129.6, 128.9 (2 C), 128.8

(2 C), 128.3 (2 C), 116.9 (d, J = 22.2 Hz), 116.3 (d, J = 22.6 Hz).

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₀H₁₅FNaO₂S₂: 393.0395;

found: 393.0395.

Mp 126–127 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.03 (s, 1 H), 7.51 (d, J = 8.3 Hz, 2 H),

7.36 (d, J = 8.1 Hz, 2 H), 7.20–7.16 (m, 4 H), 6.82–6.76 (m, 2 H), 6.75 (s,

1 H), 3.87 (s, 3 H), 3.78 (s, 3 H), 2.37 (s, 3 H), 2.36 (s, 3 H).

(E)-(4-Methoxyphenyl)[2-phenyl-2-(phenylsulfonyl)vinyl]sulfane

(3ej)

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), S-(4-methoxyphenyl) benzenesulfonothioate (2j) (210.3 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3ej as a yellow liquid

(97.5 mg, 51%, >15:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 8.03 (s, 1 H), 7.61 (d, J = 7.2 Hz, 2 H),

7.52 (t, J = 7.4 Hz, 1 H), 7.43–7.39 (m, 4 H), 7.37–7.31 (m, 3 H), 7.20

(dd, J = 7.9, 1.6 Hz, 2 H), 6.91 (d, J = 8.8 Hz, 2 H), 3.83 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 160.5, 146.1, 139.5, 135.0, 134.0 (2 C),

133.2, 130.7, 130.4 (2 C), 129.5, 128.9 (2 C), 128.8 (2 C), 128.3 (2 C),

123.2, 115.3 (2 C), 55.6.

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₁H₁₉O₂S₂: 383.0776; found:

383.0769.

These data are consistent with literature values.^10d

(E)-p-Tolyl[2-tosyl-2-(3,4,5-trimethoxyphenyl)vinyl]sulfane (3bb)

Following GP1 using 5-(bromoethynyl)-1,2,3-trimethoxybenzene

(1b) (135.5 mg, 0.5 mmol), S-p-tolyl 4-methylbenzenesulfonothioate

(2b) (208.8 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and

Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column

chromatography (silica gel, 10% EtOAc/PE) yielded the title compound

3bb as a colorless solid (148.2 mg, 63%, >5:1 mixture of E/Z isomers).

Mp 167–169 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.04 (s, 1 H), 7.54 (d, J = 8.3 Hz, 2 H),

7.36 (d, J = 8.1 Hz, 2 H), 7.22–7.17 (m, 4 H), 7.11 (s, 1 H), 6.40 (s, 1 H),

3.85 (s, 3 H), 3.73 (s, 6 H), 2.38 (s, 3 H), 2.37 (s, 3 H).

K

A. H. Kumari et al.

Paper

Synthesis

¹³C NMR (101 MHz, CDCl₃):  = 153.2, 144.3, 144.1, 139.1, 138.8,

136.6, 135.6, 131.5 (2 C), 130.4 (2 C), 130.3, 129.5 (2 C), 129.4, 128.4

(2 C), 125.9, 107.3, 106.9, 61.0, 56.2 (2 C), 21.6, 21.3.

Mp 128–130 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.13 (s, 1 H), 7.60 (d, J = 8.3 Hz, 2 H),

7.41–7.38 (m, 3 H), 7.22–7.18 (m, 5 H), 7.03 (dd, J = 5.1, 3.7 Hz, 1 H),

2.38 (s, 3 H), 2.38 (s, 3 H).

These data are consistent with literature values.^10c

These data are consistent with literature values.^10c,d

(E)-[2-(4-Methoxyphenyl)-2-tosylvinyl](p-tolyl)sulfane (3cb)

Following GP1 using 1-(bromoethynyl)-4-ethoxybenzene (1c) (105.0

mg, 0.5 mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b) (208.8

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3cb as a color-

less solid (137.5 mg, 67%, >30:1 mixture of E/Z isomers).

(E)-2-[2-(p-Tolylthio)-1-tosylvinyl]-1-tosyl-1H-indole (3mb)

Following GP1 using 2-(bromoethynyl)-1-tosyl-1H-indole (1m)

(187.1 mg, 0.5 mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b)

(208.8 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3mb as a

colorless solid (146.3 mg, 51%, >12:1 mixture of E/Z isomers).

Mp 92–94 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.06 (s, 1 H), 7.52 (d, J = 8.3 Hz, 2 H), 7.36

(d, J = 8.1 Hz, 2 H), 7.25–7.21 (m, 1 H), 7.21–7.18 (m, 4 H), 6.91–6.88 (m,

1 H), 6.78–6.75 (m, 2 H), 3.75 (s, 3 H), 2.38 (s, 3 H), 2.37 (s, 3 H).

Mp 135–138 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.23 (s, 1 H), 7.94 (d, J = 8.3 Hz, 1 H),

7.87–7.80 (m, 1 H), 7.74 (d, J = 8.3 Hz, 2 H), 7.52 (s, 1 H), 7.40 (d, J = 8.2

Hz, 2 H), 7.34–7.29 (m, 4 H), 7.24 (s, 1 H), 7.19–7.16 (m, 3 H), 7.04 (d, J

= 7.9 Hz, 2 H), 2.37 (s, 6 H), 2.33 (s, 3 H).

These data are consistent with literature values.^13,14

¹³C NMR (101 MHz, CDCl₃):  = 147.0, 145.4, 144.1, 139.3, 136.2,

135.1, 134.7, 134.0, 131.7 (2 C), 130.5 (2 C), 130.1 (2 C), 129.5 (2 C),

129.0, 128.6, 128.2 (2 C), 127.7, 127.1 (2 C), 125.2, 123.6, 121.0, 113.7,

112.3, 21.8, 21.7, 21.3.

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₃₁H₂₇NNaO₄S₃: 596.0995;

found: 596.1000.

(E)-[2-(Naphthalen-1-yl)-2-tosylvinyl](p-tolyl)sulfane (3ib)

Following GP1 using 1-(bromoethynyl)-1-naphthaene (1i) (115.5 mg,

0.5 mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b) (208.8 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3ib as a colorless

solid (127.0 mg, 59%, >30:1 mixture of E/Z isomers).

Mp 104–106 °C.

(E)-tert-Butyl 2-[2-(p-Tolylthio)-1-tosylvinyl]-1H-indole-1-

¹H NMR (400 MHz, CDCl₃):  = 8.32 (s, 1 H), 7.88 (d, J = 8.3 Hz, 1 H),

7.83 (d, J = 8.1 Hz, 1 H), 7.56 (d, J = 8.4 Hz, 1 H), 7.45–7.40 (m, 4 H),

7.35–7.30 (m, 3 H), 7.18–7.16 (m, 3 H), 7.10 (d, J = 8.0 Hz, 2 H), 2.36 (s,

3 H), 2.33 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 146.3, 144.1, 139.0, 136.0, 134.3,

133.7, 131.5 (2 C), 131.1, 130.4 (2 C), 130.2, 129.52, 129.49 (2 C),

129.2, 128.6 (2 C), 128.5, 128.0, 126.7, 126.2, 125.3, 125.1, 21.7, 21.3.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₂₆H₂₆NO₂S₂: 448.1405;

found: 448.1399.

These data are consistent with literature values.^10d

carboxylate (3nb)

Following GP1 using tert-butyl 2-(bromoethynyl)-1H-indole-1-car-

boxylate (1n) (160.1 mg, 0.5 mmol), S-p-tolyl 4-methylbenzenesul-

fonothioate (2b) (208.8 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025

mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by flash

column chromatography (silica gel, 10% EtOAc/PE) yielded the title

compound 3nb as a yellow solid (137.7 mg, 53%, >30:1 mixture of E/Z

isomers).

Mp 130–132 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.25 (s, 1 H), 7.59–7.55 (m, 3 H), 7.35

(d, J = 8.1 Hz, 2 H), 7.32–7.28 (m, 1 H), 7.21–7.14 (m, 4 H), 7.14–7.09

(m, 3 H), 2.37 (s, 3 H), 2.33 (s, 3 H), 1.67 (s, 9 H).

¹³C NMR (101 MHz, CDCl₃):  = 149.3, 146.4, 144.1, 139.1, 136.7, 131.6

(2 C), 130.4 (2 C), 129.7, 129.6 (2 C), 129.3, 128.5, 128.3 (2 C), 127.7,

125.6, 124.8, 122.8, 120.2, 115.4, 110.2, 84.5, 28.3 (3 C), 21.7, 21.3.

(E)-[2-(Naphthalen-2-yl)-2-tosylvinyl](p-tolyl)sulfane (3jb)

Following GP1 using 1-(bromoethynyl)-2-naphthaene (1j) (156.0 mg,

0.5 mmol), S-(4-tolyl) 4-methylbenzenesulfonothioate (2b) (208.79

mg, 0.75 mmol) and Cs₂CO₃(651.6 mg, 2 mmol) for 3 h. Purification

by flash column chromatography (silica gel, 10% EtOAc/PE) yielded

the title compound 3jb as a yellow solid (124.8 mg, 58%, >30:1 mix-

ture of E/Z isomers).

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₉H₂₉NNaO₄S₂: 542.1436;

found: 542.1432.

(E)-2-{[2-(3,4-Dimethoxyphenyl)-2-(thiophen-2-ylsulfonyl)-

vinyl]thio}thiophene (3af)

Mp 180–182 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.15 (s, 1 H), 7.84–7.76 (m, 3 H), 7.74

(s, 1 H), 7.53–7.46 (m, 4 H), 7.37 (d, J = 8.1 Hz, 2 H), 7.31 (dd, J = 8.5,

1.7 Hz, 1 H), 7.17 (dd, J = 15.6, 8.0 Hz, 4 H), 2.37 (s, 3 H), 2.36 (s, 3 H).

Following GP1 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), S-thiophen-2-yl thiophene-2-sulfonothioate

(2f) (131.2 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and

Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column

chromatography (silica gel, 10% EtOAc/PE) yielded the title compound

3af as a brown liquid (118.9 mg, 56%, >5:1 mixture of E/Z isomers).

These data are consistent with literature values.^10d

(E)-2-[2-(p-Tolylthio)-1-tosylvinyl]thiophene (3kb)

Following GP1 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), S-p-tolyl 4-methylbenzenesulfonothioate (2b) (208.8 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 10% EtOAc/PE) yielded the title compound 3kb as a colorless

solid (106.3 mg, 55%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 7.89 (s, 1 H), 7.59 (dd, J = 5.0, 1.3 Hz, 1

H), 7.47 (dd, J = 5.4, 1.3 Hz, 1 H), 7.35 (dd, J = 3.8, 1.3 Hz, 1 H), 7.24 (dd,

J = 3.6, 1.3 Hz, 1 H), 7.04 (dd, J = 5.4, 3.6 Hz, 1 H), 6.99 (dd, J = 4.9, 3.8

Hz, 1 H), 6.84 (d, J = 1.1 Hz, 2 H), 6.81 (s, 1 H), 3.89 (s, 3 H), 3.82 (s, 3 H).

L

A. H. Kumari et al.

Paper

Synthesis

¹³C NMR (101 MHz, CDCl₃):  = 150.2, 149.0, 145.2, 140.4, 135.9,

135.3, 134.3, 134.0, 131.4, 129.4, 128.2, 127.6, 123.3, 122.1, 112.8,

111.1, 56.1, 55.9.

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₁₈H₁₆NO₂S₃: 374.0343;

found: 374.0331.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₁₈H₂₀NO₄S₄: 442.0275;

(E)-2-[1-(Naphthalen-2-ylsulfonyl)-2-(naphthalen-2-ylthio)-

vinyl]thiophene (3ke)

found: 442.0269.

Following GP1 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), S-naphthalen-1-yl naphthalene-1-sulfonothioate (2e) (175.2

mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3

mg, 1.5 mmol) for 3 h. Purification by flash column chromatography

(silica gel, 10% EtOAc/PE) yielded the title compound 3ke as a light

yellow solid (112.3 mg, 49%, >30:1 mixture of E/Z isomers).

(E)-2-{[2-(3,4-Dimethoxyphenyl)-2-(phenylsulfonyl)vinyl]-

thio}pyridine (3ak)

Following GP1 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), S-pyridin-2-yl benzenesulfonothioate (2k)

(188.5 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 3 h. Purification by flash column chromatog-

raphy (silica gel, 10% EtOAc/PE) yielded the title compound 3ak as a

yellow liquid (109.6 mg, 53%, >7:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 9.09 (s, 1 H), 8.60–8.57 (m, 1 H), 7.69

(d, J = 7.2 Hz, 2 H), 7.58 (td, J = 7.9, 1.8 Hz, 1 H), 7.52 (tt, J = 7.4, 1.2 Hz,

1 H), 7.40 (t, J = 7.7 Hz, 2 H), 7.19 (d, J = 8.0 Hz, 1 H), 7.17–7.13 (m, 1

H), 6.80 (d, J = 8.3 Hz, 1 H), 6.73 (dd, J = 8.2, 2.0 Hz, 1 H), 6.68 (d, J = 1.9

Hz, 1 H), 3.87 (s, 3 H), 3.74 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 153.6, 150.3, 149.9, 148.9, 139.5,

138.7, 137.1, 136.5, 133.1, 128.9 (2 C), 128.5 (2 C), 123.5, 123.2, 123.1,

121.8, 112.8, 111.0, 56.0, 55.9.

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₂₁H₁₉NNaO₄S₂: 436.0653;

found: 436.0648.

Mp 150–152 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.38 (s, 1 H), 8.35 (s, 1 H), 8.03 (s, 1 H),

7.92–7.85 (m, 6 H), 7.69 (dd, J = 8.7, 1.8 Hz, 1 H), 7.65–7.61 (m, 1 H),

7.59–7.55 (m, 4 H), 7.41 (dd, J = 5.1, 1.1 Hz, 1 H), 7.24 (dd, J = 3.7, 1.1

Hz, 1 H), 7.02 (dd, J = 5.1, 3.7 Hz, 1 H).

These data are consistent with literature values.^10c

tert-Butyl (E)-2-[1-(Naphthalen-2-ylsulfonyl)-2-(naphthalen-2-

ylthio)vinyl]-1H-indole-1-carboxylate (3ne)

Following GP1 using tert-butyl 2-(bromoethynyl)-1H-indole-1-car-

boxylate (1n) (160.1 mg, 0.5 mmol), S-naphthalen-2-yl naphthalene-

2-sulfonothioate (2e) (175.2 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg,

0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by

flash column chromatography (silica gel, 10% EtOAc/PE) yielded the

title compound 3ne as a yellow solid (145.0 mg, 49%, >30:1 mixture of

E/Z isomers).

(E)-2-{[2-(Thiophen-2-yl)-2-(thiophen-2-ylsulfonyl)vi-

nyl]thio}thiophene (3kf)

Following GP1 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), S-thiophen-2-yl thiophene-2-sulfonothioate (2f) (131.2 mg,

0.75 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg,

1.5 mmol) for 3 h. Purification by flash column chromatography (sili-

ca gel, 8% EtOAc/PE) yielded the title compound 3kf as a brown solid

(88.9 mg, 48%, >30:1 mixture of E/Z isomers).

Mp 99–101 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.49 (s, 1 H), 8.30 (d, J = 1.5 Hz, 1 H),

7.97 (d, J = 1.6 Hz, 1 H), 7.89–7.81 (m, 7 H), 7.69 (dd, J = 8.7, 1.8 Hz, 1

H), 7.63–7.58 (m, 1 H), 7.56–7.52 (m, 6 H), 7.17 (d, J = 7.8 Hz, 1 H),

7.07 (t, J = 7.5 Hz, 1 H), 1.59 (s, 9 H).

¹³C NMR (101 MHz, CDCl₃):  = 149.2, 146.2, 136.4, 135.1, 133.6,

133.0, 132.1, 130.6, 130.5, 130.0, 129.8, 129.6, 129.5, 129.3, 129.1,

129.0, 128.1, 128.03, 127.99 (2 C), 127.8, 127.5, 127.33, 127.28, 127.2,

125.0, 123.1, 122.9, 120.1, 115.5, 110.1, 84.5, 28.2 (3 C).

Mp 120–122 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.99 (s, 1 H), 7.60 (dd, J = 5.0, 1.3 Hz, 1

H), 7.49 (dd, J = 5.4, 1.3 Hz, 1 H), 7.47 (d, J = 1.1 Hz, 1 H), 7.45 (td, J =

1.6 Hz, 1 H), 7.30–7.26 (m, 2 H), 7.07 (td, J = 5.4, 3.6 Hz, 2 H), 7.02 (dd,

J = 5.0, 3.8 Hz, 1 H).

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₃₅H₂₉NNaO₄S₂: 614.1436;

found: 614.1436.

¹³C NMR (101 MHz, CDCl₃):  = 146.8, 140.2, 135.5, 134.4, 134.2,

133.4, 131.6, 131.1, 129.9, 129.5, 129.1, 128.3, 127.6, 127.4.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₁₄H₁₄NO₂S₅: 387.9628;

tert-Butyl (E)-2-[1-(naphthalen-1-ylsulfonyl)-2-(naphthalen-1-

ylthio)vinyl]-1H-indole-1-carboxylate (3nn)

found: 387.9623.

Following GP1 using tert-butyl 2-(bromoethynyl)-1H-indole-1-car-

boxylate (1n) (160.1 mg, 0.5 mmol), S-naphthalen-1-yl naphthalene-

1-sulfonothioate (2n) (175.2 mg, 0.75 mmol), NiCl₂·6H₂O (5.9 mg,

0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for 3 h. Purification by

flash column chromatography (silica gel, 10% EtOAc/PE) yielded the

title compound 3nn as a colorless solid (139.0 mg, 47%, >30:1 mixture

of E/Z isomers).

(E)-2-{[2-(Thiophen-2-yl)-2-tosylvinyl]thio}pyridine (3kl)

Following GP1 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), S-pyridin-2-yl benzenesulfonothioate (2l) (199.0 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 8% EtOAc/PE) yielded the title compound 3kl as a yellow liquid

(85.9 mg, 46%, >30:1 mixture of E/Z isomers).

¹H NMR (400 MHz, CDCl₃):  = 9.21 (s, 1 H), 8.61–8.58 (m, 1 H), 7.65

(d, J = 8.3 Hz, 2 H), 7.63–7.59 (m, 2 H), 7.40 (dd, J = 5.1, 1.2 Hz, 1 H),

7.24 (d, J = 8.0 Hz, 1 H), 7.21 (d, J = 8.6 Hz, 2 H), 7.17 (dd, J = 3.6, 1.2 Hz,

1 H), 7.02 (dd, J = 5.1, 3.7 Hz, 1 H), 2.37 (s, 3 H).

Mp 106–108 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.49 (s, 1 H), 8.30 (s, 1 H), 8.13 (d, J =

8.3 Hz, 1 H), 7.97 (s, 1 H), 7.89–7.81 (m, 6 H), 7.70 (dd, J = 8.7, 1.8 Hz, 1

H), 7.64–7.57 (m, 2 H), 7.57–7.50 (m, 5 H), 7.17 (d, J = 7.8 Hz, 1 H),

7.07 (t, J = 7.5 Hz, 1 H), 1.59 (s, 9 H).

¹³C NMR (101 MHz, CDCl₃):  = 149.2, 146.2, 136.3, 135.1, 133.6,

133.0, 132.1, 130.5, 130.0, 129.8, 129.6, 129.5, 129.3, 129.1, 129.0,

128.2, 128.1, 128.0 (2 C), 127.9, 127.8, 127.5, 127.33, 127.29, 127.2,

125.0, 123.1, 123.0, 120.1, 115.5, 110.1, 84.5, 28.2 (3 C).

¹³C NMR (101 MHz, CDCl₃):  = 153.2, 150.3, 149.6, 144.2, 139.5,

137.5, 137.2, 136.4, 130.5, 129.6, 128.6, 128.3, 127.2, 123.2, 122.0,

121.2, 119.8, 21.7.

M

A. H. Kumari et al.

Paper

Synthesis

HRMS (ESI-TOF): m/z [M + Na]⁺calcd for C₃₅H₂₉NNaO₄S₂: 614.1436;

found: 614.1432.

(487.3 mg, 1.5 mmol) for 2 h. Purification by flash column chromatog-

raphy (silica gel, 5% EtOAc/PE) yielded the title compound 7ab as a

colorless solid (179.7 mg, 88%).

(S)-1-Phenyl-2-(phenylselanyl)-2-(phenylsulfonyl)ethanone (4)

Mp 78–80 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.40 (d, J = 8.1 Hz, 2 H), 7.19–7.14 (m, 4

H), 7.10 (dd, J = 8.3, 2.2 Hz, 1 H), 7.06 (d, J = 2.1 Hz, 1 H), 7.02 (s, 1 H),

6.99 (d, J = 8.0 Hz, 2 H), 6.73 (d, J = 8.4 Hz, 1 H), 3.83 (s, 3 H), 3.80 (s, 3

H), 2.36 (s, 3 H), 2.25 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 148.70, 148.68, 137.7, 136.0, 134.1,

132.02, 131.98, 131.2, 130.9 (2 C), 130.1 (2 C), 129.8, 129.7 (2 C),

129.0 (2 C), 119.5, 110.9, 110.3, 55.9 (2 C), 21.2, 21.1.

Following GP1 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), Se-phenyl benzenesulfonoselenoate (2o) (222.9 mg, 0.75

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 3 h. Purification by flash column chromatography (silica

gel, 8% EtOAc/PE) yielded the title compound 4 as a yellow solid

(101.6 mg, 49%).

Mp 100–102 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.02 (dd, J = 8.4, 1.1 Hz, 2 H), 7.76 (dd,

J = 8.4, 1.1 Hz, 2 H), 7.63 (t, J = 7.5 Hz, 1 H), 7.59–7.50 (m, 5 H), 7.42–

7.38 (m, 2 H), 7.35 (d, J = 7.4 Hz, 1 H), 7.28–7.24 (m, 2 H), 5.79 (s, 1 H).

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₄H₂₅O₂S₂: 409.1296; found:

409.1281.

¹³C NMR (101 MHz, CDCl₃):  = 189.5, 137.1, 135.9 (2 C), 135.1, 134.4,

134.3, 130.7 (2 C), 129.8, 129.6 (2 C), 129.0 (2 C), 128.9 (2 C), 128.8 (2

C), 127.7, 68.2.

HRMS (ESI-TOF): m/z [M + NH₄]⁺calcd for C₂₀H₂₀NO₃SSe: 434.0329;

found: 434.0315.

(2-Phenylethene-1,1-diyl)bis(phenylsulfane) (7ea)

Following GP2 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), 1-(phenylthio)pyrrolidine-2,5-dione (6a) (259.1 mg, 1.25

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 2 h. Purification by flash column chromatography (silica

gel, 5% EtOAc/PE) yielded the title compound 7ea as a yellow liquid

(137.8 mg, 86%).

1,1-Disulfenylethenes; General Procedure 2 (GP2)

¹H NMR (400 MHz, CDCl₃):  = 7.59–7.54 (m, 2 H), 7.52–7.47 (m, 2 H),

7.39–7.34 (m, 2 H), 7.30 (tt, J = 7.2, 1.3 Hz, 1 H), 7.27–7.22 (m, 5 H),

7.21–7.16 (m, 3 H), 7.08 (tt, J = 7.2, 1.2 Hz, 1 H).

¹³C NMR (101 MHz, CDCl₃):  = 138.9, 136.7, 135.3, 134.8, 130.7 (2 C),

129.4 (3 C), 129.0 (2 C), 128.5 (2 C), 128.3 (2 C), 127.75, 127.70, 126.9

(2 C), 126.0.

A

heat-gun-dried Schlenk tube was charged 1-bromoalkene

1(a,e,f,g,j,k,l) (0.5 mmol, 1.0 equiv), N-arylthiosuccinamide 6a,b (1.25

mmol, 2.5 equiv), NiCl₂·6H₂O (0.025 mmol, 0.05 equiv) and Cs₂CO₃

(1.5 mmol, 3.0 equiv) in DMF (2.5 mL). The reaction mixture was

stirred at 90 °C for 3 h. The progress was monitored by TLC (until the

reaction appeared to be complete or was not proceeding any further).

The mixture was quenched by the addition of H₂O (10 mL) followed

by extraction with EtOAc (3 × 20 mL). The combined organic layers

was washed with brine (2 × 20 mL), dried over anhydrous Na₂SO₄, and

the solvent was removed under reduced pressure. The resulting resi-

due was subjected to flash chromatography (silica gel, 100–200 mesh,

eluting with 5% EtOAc/PE) to afford the corresponding 1,1-disulfenyl-

ethene.

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₀H₁₇S₂: 321.0772; found:

321.0784.

(2-Phenylethene-1,1-diyl)bis(p-tolylsulfane) (7eb)

Following GP2 using (bromoethynyl)benzene (1e) (90.5 mg, 0.5

mmol), 1-(p-tolylthio)pyrrolidine-2,5-dione (6b) (276.6 mg, 1.25

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 2 h. Purification by flash column chromatography (silica

gel, 5% EtOAc/PE) yielded the title compound 7eb as a colorless solid

(139.4 mg, 80%).

[2-(3,4-Dimethoxyphenyl)ethene-1,1-diyl]bis(phenylsulfane)

(7aa)

Following GP2 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), 1-(phenylthio)pyrrolidine-2,5-dione (6a)

(259.1 mg, 1.25 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 2 h. Purification by flash column chromatog-

raphy (silica gel, 5% EtOAc/PE) yielded the title compound 7aa as a

colorless solid (161.7 mg, 85%).

Mp 76–78 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.57–7.54 (m, 2 H), 7.41 (d, J = 8.1 Hz, 2

H), 7.27–7.23 (m, 2 H), 7.20–7.15 (m, 6 H), 7.01 (d, J = 8.0 Hz, 2 H),

2.37 (s, 3 H), 2.24 (s, 3 H).

These data are consistent with literature values.¹⁶

Mp 92–94 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.52–7.49 (m, 2 H), 7.36 (t, J = 7.3 Hz, 2

H), 7.32–7.28 (m, 1 H), 7.27–7.24 (m, 2 H), 7.18 (t, J = 7.6 Hz, 2 H),

7.14–7.09 (m, 3 H), 7.07 (d, J = 2.2 Hz, 1 H), 6.74 (d, J = 8.4 Hz, 1 H),

3.83 (s, 3 H), 3.80 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 147.7, 147.6, 134.4, 133.7, 132.7,

130.7, 129.4 (2 C), 128.7, 128.2 (2 C), 128.0, 127.8 (2 C), 127.5, 126.4,

125.0, 118.4, 109.8, 109.1, 54.8 (2).

[2-(4-Isopropylphenyl)ethene-1,1-diyl]bis(phenylsulfane) (7ga)

Following GP2 using 1-(bromoethynyl)-4-isopropylbenzene (1g)

(111.5 mg, 0.5 mmol), 1-(phenylthio)pyrrolidine-2,5-dione (6a)

(259.1 mg, 1.25 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 2 h. Purification by flash column chromatog-

raphy (silica gel, 5% EtOAc/PE) yielded the title compound 7ga as a

colorless liquid (137.7 mg, 76%).

¹H NMR (400 MHz, CDCl₃):  = 7.52–7.47 (m, 4 H), 7.35 (t, J = 7.3 Hz, 2

H), 7.31–7.25 (m, 4 H), 7.19 (t, J = 7.7 Hz, 2 H), 7.13–7.07 (m, 3 H), 2.85

(sept, J = 6.9 Hz, 1 H), 1.20 (d, J = 6.9 Hz, 6 H).

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₂H₂₁O₂S₂: 381.0983; found:

381.0982.

[2-(3,4-Dimethoxyphenyl)ethene-1,1-diyl]bis(p-tolylsulfane)

(7ab)

¹³C NMR (101 MHz, CDCl₃):  = 148.6, 136.5, 136.2, 135.5, 135.1, 130.6

(2 C), 129.4 (2 C), 129.2, 129.0 (2 C), 128.0 (2 C), 127.6, 126.7 (2 C),

126.6 (2 C), 125.8, 33.8, 24.0 (2 C).

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₃H₂₃S₂: 363.1241; found:

363.1228.

Following GP2 using 4-(bromoethynyl)-1,2-dimethoxybenzene (1a)

(120.5 mg, 0.5 mmol), 1-(p-tolylthio)pyrrolidine-2,5-dione (6b)

(276.6 mg, 1.25 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

N

A. H. Kumari et al.

Paper

Synthesis

[2-(4-Isopropylphenyl)ethene-1,1-diyl]bis(p-tolylsulfane) (7gb)

Mp 78–80 °C.

¹H NMR (400 MHz, CDCl₃):  = 7.40 (d, J = 8.1 Hz, 2 H), 7.27–7.25 (m, 3

H), 7.19 (d, J = 7.9 Hz, 2 H), 7.14 (dd, J = 3.7, 1.2 Hz, 1 H), 7.11 (dd, J =

5.1, 1.2 Hz, 1 H), 7.07 (d, J = 7.9 Hz, 2 H), 6.89 (dd, J = 5.1, 3.7 Hz, 1 H),

2.38 (s, 3 H), 2.30 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 144.4, 138.0, 136.3, 136.2, 131.4,

131.2, 131.1 (2 C), 130.2 (2 C), 129.9 (2 C), 128.5 (2 C), 127.6, 124.8,

124.6, 122.7, 21.2, 21.1.

Following GP2 using 1-(bromoethynyl)-4-isopropylbenzene (1g)

(111.5 mg, 0.5 mmol), 1-(p-tolylthio)pyrrolidine-2,5-dione (6b)

(276.6 mg, 1.25 mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃

(487.3 mg, 1.5 mmol) for 2 h. Purification by flash column chromatog-

raphy (silica gel, 5% EtOAc/PE) yielded the title compound 7gb as a

colorless liquid (154.2 mg, 79%).

¹H NMR(400 MHz, CDCl₃):  = 7.48 (d, J = 8.4 Hz, 2 H), 7.39 (d, J = 8.1

Hz, 2 H), 7.19–7.15 (m, 5 H), 7.10 (d, J = 8.2 Hz, 2 H), 7.01 (d, J = 8.0 Hz,

2 H), 2.85 (sept, J = 6.9 Hz, 1 H), 2.36 (s, 3 H), 2.25 (s, 3 H), 1.20 (d, J =

6.9 Hz, 6 H).

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₀H₁₉S₃: 355.0649; found:

355.0636.

¹³C NMR (101 MHz, CDCl₃):  = 148.4, 137.7, 136.72, 136.70, 135.7,

132.0, 131.5, 131.0 (2 C), 130.1 (2 C), 129.8 (2 C), 128.9, 128.3 (2 C),

126.7 (2 C), 126.6 (2 C), 33.8, 24.0 (2 C), 21.2, 21.1.

2-[2,2-Bis(p-tolylthio)vinyl]furan (7lb)

Following GP2 using 2-(bromoethynyl)furan (1l) (85.5 mg, 0.5 mmol),

1-(p-tolylthio)pyrrolidine-2,5-dione (6b) (276.6 mg, 1.25 mmol),

NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5 mmol) for

2 h. Purification by flash column chromatography (silica gel, 5%

EtOAc/PE) yielded the title compound 7lb as a brown liquid (116.7

mg, 69%).

¹H NMR (400 MHz, CDCl₃):  = 7.47 (s, 1 H), 7.39 (d, J = 8.1 Hz, 2 H),

7.30 (d, J = 1.7 Hz, 1 H), 7.24 (d, J = 8.2 Hz, 2 H), 7.17 (d, J = 7.9 Hz, 2 H),

7.07 (d, J = 8.0 Hz, 2 H), 6.36 (d, J = 3.3 Hz, 1 H), 6.30 (dd, J = 3.4, 1.8 Hz,

1 H), 2.36 (s, 3 H), 2.29 (s, 3 H).

¹³C NMR (101 MHz, CDCl₃):  = 153.3, 142.4, 137.9, 136.5, 136.1,

131.41, 131.39, 131.1 (2 C), 130.1 (2 C), 129.9 (2 C), 128.2 (2 C), 118.0,

111.7, 107.6, 21.3, 21.2.

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₀H₁₉OS₂: 339.0877; found:

339.0867.

These data are consistent with literature values.¹⁵

[2-(Naphthalen-2-yl)ethene-1,1-diyl]bis(phenylsulfane) (7ja)

Following GP2 using 2-(bromoethynyl)naphthalene (1j) (173.3 mg,

0.5 mmol), 1-(phenylthio)pyrrolidine-2,5-dione (6a) (259.1 mg, 1.25

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 2 h. Purification by flash column chromatography (silica

gel, 5% EtOAc/PE) yielded the title compound 7ja as a colorless solid

(150.0 mg, 81%).

Mp 88–90 °C.

¹H NMR (400 MHz, CDCl₃):  = 8.06 (s, 1 H), 7.80–7.75 (m, 2 H), 7.72

(d, J = 1.6 Hz, 2 H), 7.58–7.54 (m, 2 H), 7.45–7.37 (m, 5 H), 7.36–7.30

(m, 3 H), 7.18 (t, J = 7.6 Hz, 2 H), 7.07 (tt, J = 7.2, 1.2 Hz, 1 H).

¹³C NMR (101 MHz, CDCl₃):  = 137.5, 136.2, 135.3, 134.8, 133.4,

132.9, 130.8 (2 C), 129.5 (2 C), 129.2, 129.0 (2 C), 128.33, 128.27 (2 C),

128.2, 127.8, 127.6, 126.4, 126.17, 126.04, 125.96, 124.7.

Conflict of Interest

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₂₄H₁₉S₂: 371.0928; found:

371.0913.

The authors declare no conflict of interest.

Funding Information

2-[2,2-Bis(phenylthio)vinyl]thiophene (7ka)

Following GP2 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), 1-(phenylthio)pyrrolidine-2,5-dione (6a) (259.1 mg, 1.25

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 2 h. Purification by flash column chromatography (silica

gel, 5% EtOAc/PE) yielded the title compound 7ka as a yellow liquid

(115.9 mg, 71%).

¹H NMR (400 MHz, CDCl₃):  = 7.44–7.41 (m, 2 H), 7.33–7.28 (m, 3 H),

7.27–7.25 (m, 3 H), 7.18 (t, J = 7.6 Hz, 2 H), 7.11–7.07 (m, 2 H), 7.05

(dd, J = 5.1, 1.1 Hz, 1 H), 6.82 (dd, J = 5.1, 3.7 Hz, 1 H).

We thank the Department of Science and Technology, Ministry of Sci-

ence and Technology, India, Women Scientists Scheme-A (WOS-A)

[SR/WOS-A/CS-14/2019] for financial assistance. Our special thanks

also go to the Department of Science and Technology-Promotion of

University Research and Scientific Excellence (DST-PURSE), Ministry

of Science and Technology, India (SR/PURSE Phase 2/32/G) pro-

gramme for partial funding support. R.J.R. thanks the University

Grants Commission (UGC) for a faculty position under the Faculty Re-

charge Programme. A.H.K. thanks WOS-A for her research fellowship.

¹³C NMR (101 MHz, CDCl₃):  = 144.2, 135.9, 134.9, 134.8, 130.7 (2 C),

129.5 (2 C), 129.1 (2 C), 128.1 (2 C), 127.8, 127.7, 126.2, 125.0, 124.8,

122.9.

J.J.K. thanks DST Inspire for his research fellowship. Departm

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Acknowledgment

HRMS (ESI-TOF): m/z [M + H]⁺calcd for C₁₈H₁₅S₃: 327.0336; found:

327.0322.

We are grateful to OUCFRD for NMR facilities.

2-[2,2-Bis(p-tolylthio)vinyl]thiophene (7kb)

Supporting Information

Following GP2 using 2-(bromoethynyl)thiophene (1k) (93.5 mg, 0.5

mmol), 1-(p-tolylthio)pyrrolidine-2,5-dione (6b) (276.6 mg, 1.25

mmol), NiCl₂·6H₂O (5.9 mg, 0.025 mmol) and Cs₂CO₃(487.3 mg, 1.5

mmol) for 2 h. Purification by flash column chromatography (silica

gel, 5% EtOAc/PE) yielded the title compound 7kb as a yellow solid

(132.9 mg, 75%).

Supporting information for this article is available online at

https://doi.org/10.1055/a-1482-2486. Su

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Paper

Synthesis

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Article Doi

Nickel-Catalyzed Difunctionalization of Alkynyl Bromides with Thiosulfonates and N -Arylthio Succinimides: A Convenient Synthesis of 1,2-Thiosulfonylethenes and 1,1-Dithioethenes

DOI: 10.1055/a-1482-2486

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