Unique Reactivity of α-Substituted Electron-Deficient Allenes using Sulfinate Salts as Lewis Base Organocatalysts

Article abstract of DOI:10.1002/adsc.201600929

The efficient sulfinate-catalyzed intermolecular addition reaction of α-substituted allenyl sulfones and allenoates with Michael acceptors is highlighted. The sequence proceeds under mild conditions to provide a scalable and efficient access to versatile

Full text of DOI:10.1002/adsc.201600929

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DOI: 10.1002/adsc.201600929
Unique Reactivity of a-Substituted Electron-Deficient Allenes
using Sulfinate Salts as Lewis Base Organocatalysts
Thomas Martzel,a Jean-FranÅois Lohier,a Annie-Claude Gaumont,a
Jean-FranÅois Briꢀre,b and Stꢁphane Perrioa,*
a
Normandie Univ, ENSICAEN, UNICAEN, CNRS, LCMT, 14000 Caen, France
Fax : (+33)-2-3145-2865; phone: (+33)-2-3145-2884; e-mail: stephane.perrio@ensicaen.fr
Normandie Univ, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000 Rouen, France
b
Received: August 22, 2016; Revised: October 12, 2016; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201600929.
Abstract: The efficient sulfinate-catalyzed intermo- enriches the diversity of Lewis base organocatalysts
lecular addition reaction of a-substituted allenyl sul- in the field of allene chemistry, in addition to the
fones and allenoates with Michael acceptors is high- well-established phosphine and amine catalysts.
lighted. The sequence proceeds under mild condi-
tions to provide a scalable and efficient access to ver-
satile functionalized alkynes, displaying a quaternary Keywords: alkynes; allenes; organic catalysis; sulfi-
stereocentre at the propargylic position. This work nates; synthetic methods
Introduction
the annulation process to an a-methyl allenyl sulfone
[R1 =Me, Eq. (2)].[6a]
Functionalized allene derivatives have emerged as
This result is in sharp contrast with an early obser-
useful platforms for the rapid construction of complex vation of Padwa and co-workers involving the same
molecules.[1,2] The unique stereoelectronic properties a-substituted allene and methyl vinyl ketone [Eq.
of these three carbon-based systems allowed the in- (3)].[4b] The reaction, carried out in refluxing THF
vestigation of versatile reactivities under catalytic (668C) and in the presence of a catalytic amount of
conditions. In the arena of organocatalysis, phos- PhSO2Na, did not furnish the standard sulfonylcyclo-
phines[3] stand out as efficient Lewis bases to trigger pentene, but instead the isomeric alkynyl sulfone D.
regioselective functionalization processes of alle- To explain the formation of this acyclic product, the
noates [Scheme 1, Eq. (1)]. Through an initial nucleo- authors suggested an initial hydrogen abstraction, at
philic attack at the central carbon atom of the cumu- the g-position of the allenyl sulfone, by the sulfur cat-
lene (b-carbon), the resulting zwitterion undergoes alyst to generate
a transient propargyl sulfone
formal [3+2] cycloadditions in the presence of elec- anion.[7] To the best of our knowledge, this single ex-
tron-poor alkenes to provide the so-called a- or g-cy- ample did not receive further attention, despite the
clopentene adducts A and B. In 1988, Padwa et al. obvious attractive synthetic values of such building
described an original alternative based on the catalyt- blocks displaying three distinct functional groups,
ic activity of sodium benzenesulfinate (PhSO2Na) along with a quaternary sterogenic centre.[8]
with parent allenyl sulfone [R1 =H, Eq. (2)].[4] This
We hypothesized that this type of chiral trifunction-
sequence encompasses an anionic formal [3+2] cyclo- al compounds could be produced through a different
addition with standard Michael acceptors [EWG= reaction pathway, in which the sulfinate catalyst[9]
CN, C(O)Me], leading to complementary cyclopen- would not initially behave as a Brønsted base, but as
tenyl structures C.[5] Only recently, the groups of a Lewis base like in the classical Padwa reaction [Eq.
Garcꢂa Ruano and Hale reported, independently, dia- (4)]. The triple bond[10] would be ultimately formed
stereoselective versions using chiral cyclic enones,[6] by an internal carbanion-promoted E2 type elimina-
which resulted in the elaboration of more complex or tion reaction.[11] This mechanistic proposal would be
naturally occurring compounds. During this investiga- compatible with the use of various catalytic sulfinate
tion, Garcꢂa Ruano extended also for the first time anions[12] (Figure 1), thus allowing a complete steric
and electronic modulation of the intermediate anionic
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which was successfully investigated with both allenyl
sulfones (EWG1 =SO2R) and allenoates (EWG1 =
CO2Et).
Results and Discussion
Our study commenced by examining on a 0.1 mmol
scale the model reaction between a-methyl allenyl
sulfone 1a and an excess of acrylonitrile 2a (3 equiv.)
to furnish alkynyl product 3aa (Figure 1 and Table 1).
A first set of experiments was carried out in THF,
and in the presence of a catalytic amount of commer-
cial sodium benzenesulfinate S1 (5 mol%). After var-
iation of the solvent amount from 10 mL to 0.1 mL
and the temperature in the range of 10–708C,
a modest but proof-of-principle result was obtained,
at ambient temperature, with a concentrated medium
of 1M (entry 1). The alkynyl target 3aa was isolated
after 24 h of reaction in a 15% yield, along with trace
Table 1. Optimization with allenyl sulfone 1a.[a]
Entry
Sulfinate
Solvent
3aa [%][b,c]
4 [%][b]
1
2
3
4
5
6
7
8
S1
S1
S1
S1
S1
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
S10
S10
THF
15
23
69
16
0
0
77
92
<5
<5
7
59
0
0
6
<5
AcOEt
CH3CN
DMF
CH2Cl2
PhH
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
Scheme 1. Nucleophilic organocatalytic reactions with elec-
tron-deficient allenes and Michael acceptors.
9
81
<5
10
11
12
13
14
15
16
17
85
0
90 (90)[d]
0 (0)[d]
92
0
0
0
0
0
85 (96)[d]
68[d,e]
98[d,f]
0 (0)[d]
0
0
[a]
Reaction conditions: 1a (0.1 mmol) and acrylonitrile 2a
(0.3 mmol), in the presence of sulfinate salt S (5 mol%)
in solvent (0.1 mL) at room temperature for 24 h.
Yield of isolated product.
Structure of 3aa was confirmed by single-crystal X-ray
analysis (see the Supporting Information).
Yields in the presence of (n-Bu)4NBr (5 mol%).
With 1 equiv. of 2a.
Figure 1. Sulfinate salts S used in this study.
[b]
[c]
species. Accordingly, we could benefit from the tuna-
bility of the proposed covalent organocatalysis ap-
proach and the nature of the cation (Na+ or R4N+).[13]
We wish to report herein the results of this study,
[d]
[e]
[f]
With 10 equiv. of 2a.
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Table 2. Scope of the methodology in the allenyl sulfone ser-
amounts of the cyclic product 4. The impact of the
solvent nature was then examined. Whereas no bene-
ficial effect was observed in ethyl acetate (23% yield
for 3aa, entry 2), a significant improvement was ob-
served in acetonitrile furnishing 3aa in 69% yield
(entry 3). However, the formation of side-product 4
was still detected (7% yield). A detrimental effect of
DMF was observed (16% yield), leading to an inverse
selectivity in favour of the unwanted cyclic isomer 4
(59% yield, entry 4). Finally, none of the previous
products 3aa or 4 were detected in dichloromethane
or benzene solutions (entries 5 and 6).
ies.[a,b]
Six sodium arenesulfinates S2–S7, displaying dis-
tinct structural features, were then evaluated (en-
tries 7–12). All of them showed promising catalytic
activities, from which the sterically encumbered 2-tol-
uenesulfinate S6 and [2.2]paracyclophan-4-ylsulfinate
S7 emerged. Both of them led exclusively to alkyne
3aa in excellent 90 and 92% yields (entries 11 and
12). More contrasted results were then obtained with
aliphatic mediators. No catalytic activity was observed
with sulfinates S8 and S9, possessing respectively an
adamantyl and a bornyl skeleton (entries 13 and 14).
Gratifyingly, the less hindered and commercial
sodium methanesulfinate S10 led essentially to 3aa in
an 85% yield (entry 15).
An improved 96% yield was achieved upon phase-
transfer catalysis (PTC) by means of 5 mol% of (n-
Bu)4NBr (entry 15). Interestingly, these PTC condi-
tions were ineffective in the presence of the aromatic
catalyst S6 (entry 11). The last adjustment focussed
on the amount of acrylonitrile 2a. Whereas a slight
erosion of the yield was observed with a stoichiometric
amount of 2a (68%, entry 16), a larger excess of 10
[a]
Reaction conditions: 1a (0.1 mmol) and Michael acceptor
(0.3 mmol), in the presence of MeSO2Na S10 (5 mol%)
and (n-Bu)4NBr (5 mol%) in CH3CN (0.1 mL) at room
temperature for 24 h.
Yield of isolated product.
On a 1.4 mmol scale.
With 1 equiv. of 2e.
On a 2.5 mmol scale with S6 and 1 equiv. of 2e.
Me3BnNCl was used instead of (n-Bu)4NBr.
With S6 (5 mol%).
[b]
[c]
[d]
[e]
[f]
[g]
equivalents led to a comparable result to that previ- sulfone (2e) led to the anticipated alkyne targets 3aa–
ously obtained with only 3 equivalents (98% yield ae in satisfactory yields, ranging from 45 to 99%. A
versus 96%, entry 17). To summarize, the best condi- similar efficiency for the construction of 3ae was ob-
tions we identified with the prototypal reaction in- served with a stoichiometric amount of vinyl sul-
volve a combination of commercial sodium methane- fone.[17] Interestingly, the reaction could also be scaled
sulfinate S10 and (n-Bu)4NBr (5 mol% each), in the up to give 0.84 g of 3ae in a 93% yield. Divinyl sul-
presence of an excess of the Michael acceptor fone was also identified as a suitable substrate, afford-
(3 equiv.).[14] The salient features of this protocol in- ing adduct 3af in a 71% yield.[18]
clude a low catalytic loading (5 mol%), the use of
A diastereoselective version was also developed
mild conditions in terms of temperature (room tem- using enantiopure furanone derivative 2g, possessing
À
perature) and base (pKa of MeSO2H/MeSO2 ꢀ2 in a menthyloxy group at position 5. The reaction, medi-
water)[15] and an operational simplicity. A control ex- ated by a catalytic system consisting of MeSO2Na and
periment, performed without acrylonitrile 2a, shed Me3BnNCl combination, led to the formation of only
light on the robustness of the allenyl sulfone 1a in the two diastereoisomers, out of the four of 3ag, in a 4:1
reaction mixture.[16] Hence, slow addition of the cu- ratio and in a 54% yield.[19] Purification on silica gel
mulene by means of a syringe-pump has been found furnished the major isomer 3ag in a satisfactory 31%
to be unnecessary, in contrast to Padwa-type reactions yield. The relative and absolute (1’S,4R,5R) configura-
involving parent allenyl sulfone.
tions were assigned by a single crystal X-ray analy-
Then, the compatibility with Michael acceptors 2, sis.[20]
incorporating various functional groups, was probed
The variation of the allenyl sulfone partner 1b–
in combination with 1a (Table 2). Acrylonitrile (2a), e was also allowed and gave rise to the formation of
methyl acrylate (2b), phenyl vinyl ketone (2c), 4- a series of a-substituted propargylic sulfones (R1)
chlorophenyl ethenesulfonate (2d) and phenyl vinyl 3be–ee, displaying elongated carbon chains or a silyl-
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A
The process was also successfully extended in the
89%. On the other hand, the reaction proceeded with allenoate series. However, it was necessary to define
allenes 1f and 1g possessing methylsulfonyl and new conditions through the modulation of the catalyt-
[2.2]paracyclophan-4-ylsulfonyl substituents to furnish ic sulfinate ion pairs. This novel optimization survey
the corresponding products 3fe and 3ge in 86 and was performed with a-methyl allenoate 5a and phenyl
53% yields, respectively. An improved 62% yield for vinyl sulfone 2e, as summarized in Table 3 (see
the latter product 3ge was obtained with sulfinate S6 Figure 1 for the structures of sulfinates S). The best
instead, but 1:1 diastereoisomeric ratios were invaria- result, leading to alkyne 6ae a 77% yield, was ob-
bly measured.
tained in DMF solution with sodium benzenesulfinate
The protocol was also amenable to a g-substituted S1 (5 mol%) as the mediator. The highly polar
substrate (Scheme 2). Treatment of g-methyl com- medium now used simplifies also the protocol, as the
pound 1h with phenyl vinyl sulfone 2e, in the pres- PT reagent is not required.
ence of sodium 2-toluenesulfinate S6 and (n-Bu)4NBr,
afforded cleanly alkyne 3he (72% yield). In this case,
two molecules of electrophile have reacted, thus high-
Table 3. Optimization with allenoate 5a.[a]
lighting a double functionalization in action.
Entry
Sulfinate
PTC
Solvent
6ae [%][b]
1
2
3
4
5
6
S10
S10
S6
S1
S7
(n-Bu)4NBr
CH3CN
DMF
DMF
DMF
DMF
DMF
0
–
–
–
–
–
68
62
77
0
Scheme 2. Extension with g-methyl allenyl sulfone 1h.
S9
0
[a]
Reaction conditions: 5a (0.1 mmol) and phenyl vinyl sul-
fone 2e (0.3 mmol), in the presence of sulfinate salt S
(5 mol%) and PTC (5 mol%), in solvent (0.1 mL) at
room temperature for 24 h.
Limitations of the process were, however, observed
with the compounds depicted in Figure 2. The use of
a,b-unsaturated amide 2h [EWG=C(O)NMe2], sulf-
oxide 2i [EWG=S(O)Ph], phosphonate 2j [EWG=
P(O)(OMe)2], aldehyde 2k (EWG=CHO), and diac-
tivated alkene 2l did not allow the isolation of the
corresponding alkynyl target. Two distinct reaction
[b]
Yield of isolated product.
Subsequently, as outlined in Table 4, we widened
outcomes have been observed, which resulted in the substrate scope by reacting with the same efficien-
either (i) the recovery of the Michael acceptor (2h–j) cy other a-substituted allenoates 5b–d. It was particu-
or (ii) its full consumption (2k and 2l), as probably larly noteworthy that the tosyl group in precursor 5d
a polymerization event[21] triggered by the sulfinate was not affected through further nucleophilic substitu-
catalyst. With respect to the allenic precursors, a- tion pathways. The process was also suitable for use
phenyl and a-ethyl-g-methyl derivatives 1i and 1j of methyl acrylate (2b), acrylonitrile (2a) and 5-
were totally inert, thus showing the impact of elec- ethoxyACTHNUTRGNEUNG
furanone (2m)[19] albeit furnishing the corre-
tronic effects and steric hindrance of these substrates. sponding adducts 6 with slightly reduced yields (33–
Moreover, messy reactions were observed with the 57%). This approach complements Hammondꢄs strat-
more sensitive allenyl sulfone 1k, probably because of egy describing the intermolecular Michael addition of
competing polymerization issues.[22]
a,g-disubstituted allenoates, initiated by catalytic de-
protonation with TBAF.[7b]
To establish which of the two possible modes of
action of the sulfinate anion (Scheme 1), as a Brønsted
base [Eq. (3)] or as a Lewis base [Eq. (4)], is more
likely, we prepared allenyl substrate 1l displaying a ter-
minal leaving group on the a-carbon chain (top of
Scheme 3).[7a,23] Subjecting tosyloxy allenyl sulfone 1l
to a stoichiometric amount of sodium benzenesulfi-
nate yielded the densely functionalized disulfonylcy-
clopropane 7 in an excellent 75% yield (path A). This
result established undoubtedly the nucleophilic be-
Figure 2. Limitations of the methodology.
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Table 4. Scope of the methodology in the allenoate series.[a,b]
1
with the analysis of H NMR spectra of products 7
and 9 and 10, indicates also that the ambident sulfi-
nate reagent has reacted invariably by its soft sulfur
centre.
According to these experimental results, we pro-
pose the sulfinate-mediated catalytic cycle highlighted
in Figure 3. The equilibrated addition reaction of the
sulfinate catalyst on the electrophilic b carbon atom
of the allene might generate a small amount of inter-
[a]
Reaction conditions: 5 (0.1 mmol) and Michael acceptor
2 (0.3 mmol), in the presence of PhSO2Na S1 (5 mol%)
in DMF (0.1 mL) at room temperature for 24 h.
Yield of isolated product.
MeSO2Na S10 was used instead of PhSO2Na S1.
A single equivalent of electrophile was used.
[b]
[c]
[d]
Figure 3. Proposed sulfinate-mediated catalytic cycle.
mediate I, which can further provide the conjugated
addition intermediate II. Finally, an E2 type elimina-
tion from anionic species II leads to the formation of
the alkyne target. We assume that the electrophilic
character of the Michael acceptor plays a crucial role
in the efficiency of the process. A sufficiently reactive
Michael acceptor is required to react with intermedi-
ate I, whereas a more reactive one such as 2k or 2l
(see Figure 2) undergoes a competing polymerization
event. Furthermore, the anionic intermediate II
should be basic enough, and not too hindered, to pro-
mote the key E2 elimination event, otherwise a retro-
Michael reaction should predominate. The reaction
pathway can also be extended to the formation of the
disubstituted alkyne 3he, starting with g-methyl allen-
yl sulfone 1h (Scheme 2). The related catalytic cycle is
Scheme 3. Insights into the reaction mechanism.
haviour of the sulfinate we initially postulated. Only provided in the Supporting Information.
trace amounts (<5%) of monosulfonyl compound 8
Finally, the new trifunctional building blocks ob-
arising from a competing deprotonation process were tained by our methodology could undergo versatile
detected (path B).[20,24]
transformations (Scheme 4). A Sonogashira coupling
Similarly, the iodo allenoate 5e was successfully reaction[25] of 3ab, 6ae and 6ce with iodobenzene af-
treated with sodium benzenesulfinate to furnish cyclo- forded internal alkynyl products 11a–c, in 70–89%
pentyl sulfone 9 in 36% yield, together with sulfonyl yields [Eq. (5)]. A highly chemoselective nitrile re-
allenoate 10 (36% yield) as a result of a competitive duction (3aa) was achieved to furnish, after acid treat-
substitution of the iodo group (bottom of Scheme 3). ment with HCl, primary ammonium salt 12 in 80%
Accordingly, the Lewis base mode of action of the yield [Eq. (6)].[26] An electrophilic cyclization induced
sulfinate organocatalyst was again unambiguously es- by iodine from 11c gave rise to the formation of
tablished. This mechanistic investigation, combined 2(3H)-furanone 13 in a 76% yield [Eq. (7)].[27]
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oxidation. Melting points (mp) were obtained on a capillary
apparatus and are uncorrected. Optical rotations are report-
ed in degdmÀ1 cm3 gÀ1 and were measured at room tempera-
ture (208C) on a polarimeter using a 1 mL cell with a 1 dm
path length at 589 nm (sodium D light). IR spectra were re-
corded on an ATR-FT-IR instrument equipped with a dia-
mond ATR probe. NMR spectra were recorded at room
temperature at 400 MHz (1H) and 100 MHz (13C) The chem-
ical shifts are calibrated to TMS (dH =0.00) or residual
proton and carbon resonances of the solvent CDCl3 (dH =
7.26 and dC =77.16). Mass spectra were obtained with
a QTOF LC/MS instrument.
General Procedures for Sulfinate-Mediated Alkyne
Formation from Allenes
Allenyl sulfone 1 or allenoate 5 (0.1 mmol), Michael accept-
or (3 equiv.) and phase-transfer reagent (with 1, 5 mol%)
were solubilized in the solvent (CH3CN with 1 and DMF
with 5, 0.1 mL), and the appropriate sulfinate S (5 mol%)
was introduced in one portion. After stirring at room tem-
perature for 24 h, the reaction mixture was concentrated
under vacuum and directly purified by column chromatogra-
phy on silica gel to afford the anticipated alkyne 3 or 6.
For larger scale reactions with allenyl sulfone 1 (>
1 mmol), a slightly modified procedure is employed. Allene
1, Michael acceptor (3 equiv.) and phase-transfer reagent
(5 mol%) were solubilized in CH3CN (2M). The resulting
mixture was cooled to 08C and the appropriate sulfinate S
(5 mol%) was added. After stirring at 08C for 30 min, the
reaction mixture was allowed to warm up to room tempera-
ture with stirring for an additional 24 h and then quenched
with water. The biphasic mixture was extracted twice with
Et2O. The organic layers were dried over MgSO4 and con-
centrated under reduced pressure. Purification on silica gel
of the residue gave the expected alkyne 3.
Scheme 4. Representative transformations of the products.
Conclusions
In conclusion, we have developed an attractive orga-
nocatalytic approach for the construction of valuable
terminal alkynes from readily available electron-defi-
cient allenes and Michael acceptors mediated by a sul-
finate salt. The protocol has been demonstrated as
a robust, efficient and operationally simple method,
which proceeds smoothly with low catalyst loading
(5 mol%), adaptability to gram-scale preparations,
4-Methyl-4-(phenylsulfonyl)hex-5-ynenitrile (3aa): From
allene 1a (19.4 mg, 0.1 mmol), acrylonitrile 2a (0.02 mL,
0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and (n-Bu)4NBr
broad spectrum of substrates and possibilities for deri- (1.7 mg, 0.005 mmol) in CH3CN; yield: 22.2 mg (0.09 mmol,
96%); white solid; mp 908C; IR (neat, ATR probe): n=
vatization. This transformation extends the diversity
of Lewis base organocatalysts applicable in allene
chemistry, in addition to the more classical phosphine
and amine catalysts. Further investigations for the de-
velopment of enantioselective versions of the method-
ology are currently underway.
3265, 2924, 2249, 1447, 1297, 1284, 1146, 1069, 801, 766 cmÀ1
;
2
1H NMR (400 MHz, CDCl3): d=1.57 (s, 3H), 2.20 (ddd, J=
13.9 Hz, 3J=6.1 and 10.4 Hz, 1H), 2.45 (ddd, 2J=13.9 Hz,
3J=5.6 and 10.0 Hz, 1H), 2.61 (s, 1H), 2.67 (ddd, 2J=
16.9 Hz, 3J=6.1 and 10.0 Hz, 1H), 2.76 (ddd, 2J=16.9 Hz,
3J=5.6 and 10.4 Hz, 1H), 7.58–7.63 (m, 2H), 7.70–7.75 (m,
1H), 7.95–7.97 (m, 2H); 13C NMR (100 MHz, CDCl3): d=
13.6, 21.9, 30.9, 61.4, 78.3, 78.9, 118.7, 128.9 (ꢅ2), 131.0 (ꢅ2),
134.2, 134.6; HR-MS (ESI): m/z=270.0564, calcd. for
C13H13NO2SNa [(M+Na)+]: 270.0565.
Experimental Section
Methyl 4-Methyl-4-(phenylsulfonyl)hex-5-ynoate (3ab):
From allene 1a (19.4 mg, 0.1 mmol), methyl acrylate 2b
(0.027 mL, 0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and
nBu4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 22.4 mg
(0.081 mmol, 81%). On a larger scale, from allene 1a
(388 mg, 2.0 mmol), methyl acrylate 2b (0.54 mL, 6.0 mmol),
MeSO2Na (11 mg, 0.1 mmol) and (n-Bu)4NBr (34 mg,
0.1 mmol) in CH3CN; yield: 392 mg (1.4 mmol, 70%); col-
ourless oil; IR (neat, ATR probe): n=3287, 3246, 1733
General Considerations
Dry THF, diethyl ether, dichloromethane, acetonitrile and
toluene were obtained by passage down an activated alumi-
na column. All other reagents and solvents were used as
purchased from commercial sources. After the use of stench
thiols, all glassware and syringes were washed with bleach.
Reaction mixtures were purified by column chromatography
with silica gel Si 60 (0.040–0.063 nm). Thin layer chromatog-
raphy was carried out on silica gel 60 F254 (1.1 mm) plates
with spot detection, under UV light and/or through KMnO4
(C=O), 1445, 1429, 1300, 1287, 1212, 1144, 1070 cmÀ1
;
2
1H NMR (400 MHz, CDCl3): d=1.56 (s, 3H), 2.20 (ddd, J=
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13.8 Hz, 3J=5.6 and 11.0 Hz, 1H), 2.35 (ddd, 2J=13.8 Hz,
3-Methyl-3-(phenylsulfonyl)-5-(vinylsulfonyl)pent-1-yne
(3af): From allene 1a (19.4 mg, 0.1 mmol), divinyl sulfone 2f
(0.031 mL, 0.3 mmol), MeSO2Na (0.9 mg, 0.005 mmol) and
(n-Bu)4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 22 mg
(0.071 mmol, 71%); white solid; mp 958C; IR (neat, ATR
probe): n=3270, 2159, 2027, 1977, 1450, 1287, 1131, 1068,
2
3J=5.6 and 10.6 Hz, 1H), 2.52 (s, 1H), 2.55 (ddd, J=16.4,
2
3
3J=5.6 and 10.6, 1H), 2.65 (ddd, J=16.4, J=5.6 and 11.0,
1H), 3.68 (s, 3H), 7.54–7.60 (m, 2H), 7.67–7.72 (m, 1H),
7.97–8.00 (m, 2H); 13C NMR (100 MHz, CDCl3): d=21.2,
29.7, 30.0, 51.9, 61.9, 77.2, 80.0, 128.7 (ꢅ2), 131.1 (ꢅ2), 134.3,
134.7, 172.7; HR-MS (ESI): m/z=303.0668, calcd. for
C14H16O4SNa [(M+Na)+]: 303.0667.
1
979, 953 cmÀ1; H NMR (400 MHz, CDCl3): d=1.53 (s, 3H),
2
3
2.28 (ddd, J=13.8 Hz, J=4.2 and 12.8 Hz, 1H), 2.50 (ddd
2J=13.8 Hz, 3J=4.6 and 12.6 Hz, 1H), 2.60 (s, 1H), 3.28
(ddd, J=14.0 Hz, J=4.2 and 12.6 Hz, 1H), 3.43 (ddd, J=
5-Methyl-5-(phenylsulfonyl)hept-6-yn-2-one (3ac): From
allene 1a (19.4 mg, 0.1 mmol), methyl vinyl ketone 2c
(0.025 mL, 0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and
(n-Bu)4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 11.9 mg
(0.045 mmol, 45%); colourless oil; IR (neat, ATR probe):
n=3291, 3257, 1715 (C=O), 1583, 1448, 1356, 1293, 1277,
2
3
2
3
3
14.0 Hz, J=4.6 and 12.8 Hz, 1H), 6.23 (d, J=9.8 Hz, 1H),
6.48 (d, 3J=16.6 Hz, 1H), 6.65 (dd, 3J=9.8 and 16.6 Hz,
1H), 7.56–7.61 (m, 2H), 7.69–7.74 (m, 1H), 7.94–7.97 (m,
2H); 13C NMR (100 MHz, CDCl3): d=22.5, 28.2, 50.4, 61.0,
78.2, 79.1, 128.9 (ꢅ2), 131.0 (ꢅ2), 131.5, 134.2, 134.6, 135.6;
HR-MS (ESI): m/z=313.0568, calcd. for C14H17O4S2 [(M+
H)+]: 313.0562.
1139, 1072 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.53 (s,
2
3
3H), 2.15 (ddd, J=14.3 Hz, J=5.4 and 10.7 Hz, 1H), 2.18
(s, 3H) 2.28 (ddd, 2J=14.3 Hz, 3J=5.4 and 10.3 Hz, 1H),
2.52 (s, 1H), 2.74 (ddd, 2J=18.0 Hz, 3J=5.4 and 10.3 Hz,
(1’S,4R,5R)-5-(Menthoxy)dihydro-4-[1-methyl-1-(phenyl-
sulfonyl)ethynyl]furan-2(3H)-one (3ag): From allene 1a
(19.4 mg, 0.1 mmol), 5(R)-menthoxyfuranone 2g (23.8 mg,
0.1 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and Me3BnNCl
(0.9 mg, 0.005 mmol) in CH3CN as a 4:1 mixture of two dia-
stereoisomers; yield: 23.3 mg (0.054 mmol, 54%). A further
purification on silica gel gave the pure enantiopure major
diastereoisomer (1’S,4R,5R)-3ag (dr=100:0); yield: 13.4 mg
(0.031 mmol, 31%); white solid; mp: 1188C; [a]2D0: À24.4 (c
0.23, CHCl3); IR (neat, ATR probe): n=3246, 2926, 1788
2
3
1H), 2.83 (ddd, J=18.0 Hz, J=5.4 and 10.7 Hz, 1H), 7.54–
7.59 (m, 2H), 7.67–7.71 (m, 1H), 7.96–8.00 (m, 2H);
13C NMR (100 MHz, CDCl3): d=22.0, 28.9, 30.0, 39.1, 61.9,
77.0, 80.3, 128.7 (ꢅ2), 131.0 (ꢅ2), 134.2, 134.9, 206.7; HR-
MS (ESI): m/z=287.0724, calcd. for C14H16O3SNa [(M+
Na)+]: 287.0718.
4-Chlorophenyl 3-Methyl-3-(phenylsulfonyl)pent-4-ynesul-
fonate (3ad): From allene 1a (19.4 mg, 0.1 mmol), 4-chloro-
phenyl ethenesulfonate 2d (65.4 mg, 0.3 mmol), MeSO2Na
(0.5 mg, 0.005 mmol) and (n-Bu)4NBr (1.7 mg, 0.005 mmol)
in CH3CN; yield: 20.5 mg (0.05 mmol, 50%); colourless oil;
IR (neat, ATR probe): n=3269, 2933, 1484, 1375, 1305,
(C=O), 1449, 1368, 1309, 1185, 1153, 1118, 938 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=0.77 (d, 3J=6.9 Hz, 3H),
0.83–1.05 (m, 3H), 0.87 (d, 3J=7.0 Hz, 3H), 0.92 (d, 3J=
6.4 Hz, 3H), 1.21–1.27 (m, 1H), 1.28–1.41 (m, 1H), 1.47 (s,
1142, 1087, 1070, 862, 837 cmÀ1
CDCl3): d=1.56 (s, 3H), 2.46 (ddd, J=14.0 Hz, J=4.1 and
;
1H NMR (400 MHz,
3
3H), 1.62–1.67 (m, 2H), 2.04 (d of quint, J=2.5 and 7.0 Hz,
2
3
1H), 2.18–2.21 (m, 1H), 2.60 (s, 1H), 2.90–2.92 (m, 2H),
2
3
13.0 Hz, 1H), 2.63 (s, 1H), 2.77 (ddd, J=14.0 Hz, J=4.5
and 12.7 Hz, 1H), 3.58 (ddd, 2J=14.4 Hz, 3J=4.1 and
12.7 Hz, 1H), 3.78 (ddd, 2J=14.4 Hz, 3J=4.5 and 13.0 Hz,
1H), 7.21–7.26 (m, 2H), 7.37–7.41 (m, 2H), 7.58–7.63 (m,
2H), 7.71–7.76 (m, 1H), 7.97–8.01 (m, 2H); 13C NMR
(100 MHz, CDCl3): d=22.9, 29.5, 47.0, 60.8, 78.4, 78.9, 123.5
(ꢅ2), 128.9 (ꢅ2), 130.1 (ꢅ2), 131.0 (ꢅ2), 133.2, 134.2, 134.7,
3
3.04–3.07 (m, 1H), 3.54 (dt, J=4.2 and 10.8 Hz, 1H), 6.10
(br s, 1H), 7.58–7.62 (m, 2H), 7.71–7.75 (m, 1H), 7.97–7.99
(m, 2H); 13C NMR (100 MHz, CDCl3): d=15.6, 19.5, 20.9,
22.3, 23.1, 25.5, 29.6, 31.4, 34.3, 39.6, 45.7, 47.7, 62.5, 78.4,
78,6, 101.8, 128.9 (ꢅ2), 131.1 (ꢅ2), 134.7 (2 signals overlap-
ping), 175.19; HR-MS (ESI): m/z=455.1868, calcd. for
C24H32O5SNa [(M+Na)+]: 455.1884.
147.3; HR-MS (ESI): m/z=435.0092, calcd.
for
3-Ethyl-3,5-(diphenylsulfonyl)pent-1-yne (3be): From
allene 1b (20.8 mg, 0.1 mmol), phenyl vinyl sulfone 2e
(50.4 mg, 0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and (n-
Bu)4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 33.4 mg
(0.089 mmol, 89%); colourless oil; IR (neat, ATR probe):
n=3241, 2159, 2029, 1976, 1447, 1306, 1138, 1082, 740,
C18H17ClO5S2Na with 35Cl isotope [(M+Na)+]: 435.0104.
3-Methyl-3,5-(diphenylsulfonyl)pent-1-yne (3ae): From
allene 1a (19.4 mg, 0.1 mmol), phenyl vinyl sulfone 2e
(50.4 mg, 0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and (n-
Bu)4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 36.1 mg
(0.099 mmol, 99%). On a larger scale, from allene 1a
(485 mg, 2.5 mmol), phenyl vinyl sulfone 2e (420 mg,
2.5 mmol), sulfinate S6 (22.3 mg, 0.125 mmol) and (n-
Bu)4NBr (41 mg, 0.125 mmol) in CH3CN; yield: 840 mg
(2.32 mmol, 93%); colourless oil; IR (neat, ATR probe): n=
721 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.00 (t, 3J=
7.4 Hz, 3H), 1.76–1.86 (m, 2H), 2.26–2.38 (m, 2H), 2.59 (s,
1H), 3.45–3.59 (m, 2H), 7.50–7.55 (m, 2H), 7.58–7.62 (m,
2H), 7.66–7.72 (m, 2H), 7.84–7.86 (m, 2H), 7.91–7.93 (m,
2H); 13C NMR (100 MHz, CDCl3): d=8.7, 25.6, 27.5, 52.4,
65.7, 78.0, 79.2, 128.1 (ꢅ2), 128.8 (ꢅ2), 129.5 (ꢅ2), 130.9 (ꢅ
2), 134.0, 134.5, 134.6, 138.8; HR-MS (ESI): m/z=399.0701,
calcd. for C19H20O4S2Na [(M+Na)+]: 399.0703.
3260, 2934, 1584, 1447, 1305, 1144, 1085, 1069, 913, 725 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.50 (s, 3H), 2.25 (ddd, J=
13.7 Hz, 3J=4.3 and 12.6 Hz, 1H), 2.41 (ddd, 2J=13.7 Hz,
3J=4.8 and 12.5 Hz, 1H), 2.55 (s, 1H), 3.38 (ddd, 2J=
13.8 Hz, 3J=4.3 and 12.5 Hz, 1H), 3.50 (ddd, 2J=13.8 Hz,
3J=4.8 and 12.6 Hz, 1H), 7.53–7.61 (m, 4H), 7.67–7.72 (m,
2H), 7.88–7.93 (m, 4H); 13C NMR (100 MHz, CDCl3): d=
22.2, 28.5, 52.4, 61.9, 78.0, 79.1, 128.1 (ꢅ2), 128.8 (ꢅ2), 129.5
(ꢅ2), 130.9 (ꢅ2), 134.1, 134.2, 134.6, 138.6; HR-MS (ESI):
m/z=385.0540, calcd. for C18H18O4S2Na [(M+Na)+]:
385.0544.
2
3-(Phenylsulfonyl)-3-(2-phenylsulfonylethyl)hex-1-yne
(3ce): From allene 1c (22.2 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (50.4 mg, 0.3 mmol), MeSO2Na (0.5 mg,
0.005 mmol) and (n-Bu)4NBr (1.7 mg, 0.005 mmol) in
CH3CN; yield: 29.5 mg (0.076 mmol, 76%); colourless oil;
IR (neat, ATR probe): n=3251, 2159, 2029, 1976, 1446,
1304, 1140, 1080, 724, 686 cmÀ1
;
1H NMR (400 MHz,
CDCl3): d=0.89 (t, 3J=7.3 Hz, 3H), 1.39–1.47 (m, 2H),
Adv. Synth. Catal. 0000, 000, 0 – 0
7
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1.68–1.77 (m, 2H), 2.29–2.34 (m, 2H), 2.58 (s, 1H), 3.48–
3.52 (m, 2H), 7.51–7.55 (m, 2H), 7.58–7.62 (m, 2H), 7.66–
7.72 (m, 2H), 7.83–7.86 (m, 2H), 7.90–7.93 (m, 2H);
13C NMR (100 MHz, CDCl3): d=14.1, 17.8, 26.3, 36.0, 52.4,
65.3, 78.3, 79.1, 128.1 (ꢅ2), 128.8 (ꢅ2), 129.5 (ꢅ2), 130.9 (ꢅ
2), 134.0, 134.5, 134.6, 138.7; HR-MS (ESI): m/z=413.0857,
calcd. for C20H22O4S2Na [(M+Na)+]: 413.0865.
0.005 mmol) in CH3CN as a mixture of two diastereoisomers
in a 1:1 ratio; yield: 30.3 mg (0.062 mmol, 62%). On the
same scale, but using instead MeSO2Na as catalyst, the
product was isolated in a lower 53% yield; white solid; mp
808C; IR (neat, ATR probe): n=3257, 2929, 1446, 1303,
1143, 1086, 1050, 915, 794, 719 cmÀ1 1H NMR (400 MHz,
;
CDCl3): d=1.18 (s, 1.5H), 1.46 (s, 1.5H), 1.96–2.16 (m,
1.5H), 2.34 (dt, J=4.7 and 12.8 Hz, 0.5H), 2.38 (s, 0.5H),
2.45 (s, 0.5H), 2.84–2.92 (m, 1H), 2.98–3.36 (m, 7.5H), 3.50
(dt, J=4.7 and 12.9 Hz, 0.5H), 3.97–4.06 (m, 1H), 6.46–6.62
(m, 4H), 6.63–6.67 (m, 1H), 6.72–6.76 (m, 1H), 7.19 (br s,
1H), 7.52–7.71 (m, 3H), 7.79–7.81 (m, 1H), 7.89–7.91 (m,
1H); 13C NMR (100 MHz, CDCl3): d=21.2 (ꢅ0.5), 22.3 (ꢅ
0.5), 28.3 (ꢅ0.5), 28.6 (ꢅ0.5), 35.0 (ꢅ0.5), 35.09, 35.1 (ꢅ0.5),
36.2, 36.6 (ꢅ0.5), 36.8 (ꢅ0.5), 52.3 (ꢅ0.5), 52.6 (ꢅ0.5), 61.6,
77.7 (ꢅ0.5), 77.8 (ꢅ0.5), 78.9 (ꢅ0.5), 78.9 (ꢅ0.5), 128.0,
128.1, 129.4, 129.5, 129.76 (ꢅ0.5), 129.84 (ꢅ0.5), 132.2,
132.59 (ꢅ0.5), 132.62 (ꢅ0.5), 132.8, 133.69 (ꢅ0.5), 133.72 (ꢅ
0.5), 133.9 (ꢅ0.5), 134.0 (ꢅ0.5), 135.9 (ꢅ0.5), 136.3 (ꢅ0.5),
137.56 (ꢅ0.5), 137.59 (ꢅ0.5), 138.5 (ꢅ0.5), 138.7 (ꢅ0.5),
139.2, 139.31 (ꢅ0.5), 139.34 (ꢅ0.5), 139.69 (ꢅ0.5), 139.73 (ꢅ
0.5), 140.8 (ꢅ0.5), 140.9 (ꢅ0.5), 143.0 (ꢅ0.5), 143.3 (ꢅ0.5);
HR-MS (ESI): m/z=515.1312, calcd. for C28H28O4S2Na
[(M+Na)+]: 515.1327.
3-Benzyl-3,5-(diphenylsulfonyl)pent-1-yne (3de): From
allene 1d (27 mg, 0.1 mmol), phenyl vinyl sulfone 2e
(50.4 mg, 0.3 mmol), MeSO2Na (0.5 mg, 0.005 mmol) and (n-
Bu)4NBr (1.7 mg, 0.005 mmol) in CH3CN; yield: 25.7 mg
(0.059 mmol, 59%); white solid; mp 1968C; IR (neat, ATR
probe): n=3270, 1599, 1583, 1446, 1306, 1286, 1147, 1137,
1
1083, 999 cmÀ1; H NMR (400 MHz, CDCl3): d=2.15 (ddd,
2J=14.2 Hz, 3J=3.8 and 12.8 Hz, 1H), 2.40 (ddd, 2J=
3
14.2 Hz, J=4.7 and 12.6 Hz, 1H), 2.64 (s, 1H), 2.97 (ddd,
2J=14.2 Hz, 3J=3.8 and 12.6 Hz, 1H), 3.02 and 3.07 (AB
2
2
3
system, JAB =13.2 Hz, 1H each), 3.42 (ddd, J=14.2 Hz, J=
4.7 and 12.8 Hz, 1H), 7.12–7.15 (m, 2H), 7.21–7.30 (3H),
7.51–7.61 (m, 4H), 7.62–7.67 (m, 1H), 7.70–7.78 (m, 3H),
7.94–7.97 (m, 2H); 13C NMR (100 MHz, CDCl3): d=25.8,
40.5, 52.4, 65.7, 77.8, 80.8, 127.9, 128.1 (ꢅ2), 128.6 (ꢅ2),
129.0 (ꢅ2), 129.3 (ꢅ2), 130.6 (ꢅ2), 131.1 (ꢅ2), 133.0, 133.8,
134.5, 134.7, 138.6; HR-MS (ESI): m/z=461.0842, calcd. for
C24H22O4S2Na [(M+Na)+]: 461.0857.
4,6-(Diphenylsulfonyl)-4-(2-phenylsulfonylethyl)hex-2-yne
(3he): From allene 1h (19.4 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (33.6 mg, 0.2 mmol), sulfinate S6 (0.9 mg,
0.005 mmol) and (n-Bu)4NBr (1.7 mg, 0.005 mmol) in
CH3CN for 72 h; yield: 38.2 mg (0.072 mmol, 72%); white
solid, mp 718C; IR (neat, ATR probe): n=2924, 2160, 1978,
3-[2-(tert-Butyldimethylsilyloxy)ethyl]-3,5-(diphenylsulfo-
nyl)pent-1-yne (3ee): From allene 1e (33.8 mg, 0.1 mmol),
phenyl vinyl sulfone 2e (50.4 mg, 0.3 mmol), MeSO2Na
(0.5 mg, 0.005 mmol) and (n-Bu)4NBr (1.7 mg, 0.005 mmol)
in CH3CN; yield: 27.6 mg (0.055 mmol, 55%); colourless oil;
IR (neat, ATR probe): n=3259, 2929, 1447, 1307, 1254,
1584, 1446, 1303, 1139, 1083, 726, 686 cmÀ1
;
1H NMR
1
1146, 1080, 834, 778, 724 cmÀ1; H NMR (400 MHz, CDCl3):
(400 MHz, CDCl3): d=1.82 (s, 3H), 2.09–2.24 (m, 4H),
3.28–3.40 (m, 4H), 7.50–7.54 (m, 2H), 7.59–7.62 (m, 4H),
7.67–7.75 (m, 5H), 7.88–7.91 (m, 4H); 13C NMR (100 MHz,
CDCl3): d=3.9, 27.4 (ꢅ2), 52.0 (ꢅ2), 64.0, 71.9, 89.4, 128.1
(ꢅ4), 129.0 (ꢅ2), 129.5 (ꢅ4), 130.6 (ꢅ2), 134.0, 134.1, 134.8,
d=0.03 (s, 3H), 0.04 (s, 3H), 0.87 (s, 9H), 1.96–2.07 (m,
2
3
2H), 2.34 (ddd, J=14.7 Hz, J=5.9 and 11.4 Hz, 1H), 2.53
(ddd, 2J=14.7 Hz, 3J=5.4 and 11.2 Hz, 1H), 2.62 (s, 1H),
3.51–3.62 (m, 2H), 3.77–3.87 (m, 2H), 7.51–7.60 (m, 4H),
7.66–7.70 (m, 2H), 7.83–7.86 (m, 2H), 7.89–7.92 (m, 2H);
13C NMR (100 MHz, CDCl3): d=À5.4 (ꢅ2), 18.3, 25.9 (ꢅ3),
27.2, 35.8, 52.4, 59.4, 64.5, 78.0, 79.4, 128.1 (ꢅ2), 128.8 (ꢅ2),
129.4 (ꢅ2), 131.0 (ꢅ2), 133.9, 134.3, 134.5, 139.0; HR-MS
(ESI): m/z=529.1508, calcd. for C25H34O5S2SiNa [(M+
Na)+]: 529.1515.
138.6; HR-MS (ESI): m/z=553.0771, calcd.
for
C26H26O6S3Na [(M+Na)+]: 553.0789.
Ethyl
2-methyl-2-[2-(phenylsulfonyl)ethyl]but-3-ynoate
(6ae): From allene 5a (12.6 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (50.4 mg, 0.3 mmol) and PhSO2Na (0.9 mg,
0.005 mmol) in DMF; yield: 22.5 mg (0.077 mmol, 77%);
colourless oil; IR (neat, ATR probe): n=3267, 2159, 2030,
3-Methyl-3-(methylsulfonyl)-5-(phenylsulfonyl)pent-1-yne
(3fe): From allene 1f (13.2 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (50.4 mg, 0.3 mmol), MeSO2Na (0.5 mg,
0.005 mmol) and (n-Bu)4NBr (1.7 mg, 0.005 mmol) in
CH3CN; yield: 25.8 mg (0.086 mmol, 86%); colourless solid;
mp 1098C; IR (neat, ATR probe): n=3256, 2159, 2030,
1976, 1731 (C=O), 1447, 1299, 1257, 1144, 1086 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.24 (t, 3J=7.2 Hz, 3H),
1.47 (s, 3H), 2.01 (dt, J=4.6 and 12.4 Hz, 1H), 2.22 (dt, J=
4.6 and 13.1 Hz, 1H), 2.32 (s, 1H), 3.25 (dt, J=4.6 and
3
13.8 Hz, 1H), 3.34 (dt, J=4.6 and 13.8 Hz, 1H), 4.16 (q, J=
1976, 1447, 1301, 1282, 1142, 1084, 953 cmÀ1
;
1H NMR
7.2 Hz, 2H), 7.56–7.60 (m, 2H), 7.65–7.69 (m, 1H), 7.90–
7.93 (m, 2H); 13C NMR (100 MHz, CDCl3): d=14.0, 25.9,
32.2, 41.7, 52.9, 62.1, 72.8, 82.9, 128.0 (ꢅ2), 129.4 (ꢅ2), 133.8,
138.9, 171.6; HR-MS (ESI): m/z=317.0824, calcd. for
C15H18O4SNa [(M+Na)+]: 317.0829.
2
(400 MHz, CDCl3): d=1.61 (s, 3H), 2.24 (ddd, J=13.7 Hz,
2
3
3J=4.2 and 12.6 Hz, 1H), 2.46 (ddd J=13.7 Hz, J=4.7 and
12.5 Hz, 1H), 2.68 (s, 1H), 3.01 (s, 3H), 3.36 (ddd, 2J=
13.8 Hz, 3J=4.2 and 12.5 Hz, 1H), 3.50 (ddd, 2J=13.8 Hz,
3J=4.7 and 12.6 Hz, 1H), 7.57–7.62 (m, 2H), 7.67–7.71 (m,
1H), 7.90–7.93 (m, 2H); 13C NMR (100 MHz, CDCl3): d=
21.7, 27.8, 35.5, 52.3, 59.7, 78.0, 79.1, 128.1 (ꢅ2), 129.5 (ꢅ2),
134.1, 138.5; HR-MS (ESI): m/z=323.0388, calcd. for
C13H16O4S2Na [(M+Na)+]: 323.0399.
Ethyl
2-benzyl-2-[2-(phenylsulfonyl)ethyl]but-3-ynoate
(6be): From allene 5b (20.2 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (50.4 mg, 0.3 mmol) and PhSO2Na (0.9 mg,
0.005 mmol) in DMF; yield 32.6 mg (0.088 mmol, 88%); col-
ourless oil; IR (neat, ATR probe): n=3272, 1729 (C=O),
1
3-Methyl-3-([2.2]paracyclophan-4-ylsulfonyl)-5-(phenyl-
sulfonyl)pent-1-yne (3ge): From allene 1g (32.4 mg,
0.1 mmol), phenyl vinyl sulfone 2e (50.4 mg, 0.3 mmol), sul-
finate salt S6 (0.9 mg, 0.005 mmol) and (n-Bu)4NBr (1.7 mg,
1496, 1446, 1305, 1221, 1144, 1085, 1016, 740 cmÀ1; H NMR
3
(400 MHz, CDCl3): d=1.17 (t, J=7.2 Hz, 3H), 2.07 (dt, J=
4.0 and 12.9 Hz, 1H), 2.31 (dt J=4.4 and 12.9 Hz, 1H), 2.43
2
(s, 1H), 3.01 and 3.11 (AB system, JAB =13.2 Hz, 1H each),
Adv. Synth. Catal. 0000, 000, 0 – 0
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3.18 (dt, J=4.4 and 12.9 Hz, 1H), 3.39 (dt, J=4.0 and
12.9 Hz, 1H), 4.11 (q, J=7.2 Hz, 2H), 7.18–7.21 (m, 2H),
ATR probe): n=3283, 2249, 1727 (C=O), 1496, 1455, 1446,
3
1369, 1224, 1191, 1087, 1016 cmÀ1
;
1H NMR (400 MHz,
3
2
7.26–7.29 (m, 3H), 7.57–7.61 (m, 2H), 7.66–7.71 (m, 1H),
7.90–7.92 (m, 2H); 13C NMR (100 MHz, CDCl3): d=13.9,
31.0, 45.0, 48.2, 52.9, 62.1, 75.3, 81.5, 127.4, 128.0 (ꢅ2), 128.2
(ꢅ2), 129.3 (ꢅ2), 130.1 (ꢅ2), 133.8, 135.0, 138.9, 170.6; HR-
MS (ESI): m/z=393.1130, calcd. for C21H22O4SNa [(M+
Na)+]: 393.1137.
CDCl3): d=1.22 (t, J=7.1 Hz, 3H), 1.95 (ddd, J=13.1 Hz,
3J=4.7 and 10.6 Hz, 1H), 2.33 (ddd, 2J=13.1 Hz, 3J=5.7
and 10.6 Hz, 1H), 2.44 (ddd, 2J=16.5 Hz, 3J=5.7 and
2
3
10.6 Hz, 1H), 2.48 (s, 1H), 2.61 (ddd, J=16.5 Hz and J=
4.7 and 10.6 Hz, 1H), 3.08 and 3.14 (AB system, 2J=
3
13.2 Hz, 1H each), 4.23 (q, J=7.1 Hz, 2H), 7.22–7.33 (m,
Ethyl 2-ethynyl 2-[2-(phenylsulfonyl)ethyl]pent-4-enoate
(6ce): From allene 5c (15.2 mg, 0.1 mmol), phenyl vinyl sul-
fone 2e (50.4 mg, 0.3 mmol) and PhSO2Na (0.9 mg,
0.005 mmol) in DMF; yield: 26.4 mg (0.083 mmol, 83%);
colourless oil; IR (neat, ATR probe): n=3271, 1731 (C=O),
5H); 13C NMR (100 MHz, CDCl3): d=13.8, 14.0, 33.6, 45.1,
48.6, 62.3, 75.6, 81.3, 119.0, 127.5, 128.2 (ꢅ2), 130.2 (ꢅ2),
134.9, 170.7; HR-MS (ESI): m/z=278.1171, calcd. for
C16H17NO2Na [(M+Na)+]: 278.1157.
1-Ethyl 5-methyl 2-Ethynyl-2-methylpentanedioate (6ab):
From allene 5a (12.6 mg, 0.1 mmol), methyl acrylate 2b
(0.027 mL, 0.3 mmol) and PhSO2Na (0.9 mg, 0.005 mmol) in
DMF; yield: 11.0 mg (0.052 mmol, 52%); colourless oil; IR
(neat, ATR probe): n=3274, 2985, 1732 (C=O), 1447, 1376,
1
1446, 1306, 1218, 1146, 1086, 925, 744, 687 cmÀ1; H NMR
3
(400 MHz, CDCl3): d=1.23 (t, J=7.1 Hz, 3H), 2.03 (dt, J=
4.1 and 12.9 Hz, 1H), 2.20 (dt J=4.4 and 13.1 Hz, 1H), 2.37
2
(s, 1H), 2.43 and 2.53 (AB part of ABX system, JAB
=
3
3
13.6 Hz, JAX =7.3 Hz and JBX =7.1 Hz, 1H each), 3.16 (dt,
J=4.4 and 12.9 Hz, 1H), 3.35 (dt, J=4.1 and 13.1 Hz, 1H),
4.09–4.21 (m, 2H), 5.07–5.12 (m, 2H), 5.75 (ddt, 3J=10.4,
17.6 and 7.2 Hz, 1H) 7.55–7.60 (m, 2H), 7.65–7.69 (m, 1H),
7.89–7.92 (m, 2H); 13C NMR (100 MHz, CDCl3): d=14.1,
30.4, 43.3, 46.4, 52.8, 62.1, 74.2, 81.4, 119.7, 128.0 (ꢅ2), 129.3
(ꢅ2), 131.7, 133.8, 138.9, 170.6; HR-MS (ESI): m/z=
343.0981, calcd. for C17H20O4SNa [(M+Na)+]: 343.0980.
Ethyl 2-[4-(4-methylphenylsulfonyloxy)butyl]-2-[2-(phe-
nylsulfonyl)ethyl]but-3-ynoate (6de): From allene 6d
(33.8 mg, 0.1 mmol), phenyl vinyl sulfone 2e (50.4 mg,
0.3 mmol) and PhSO2Na (0.9 mg, 0.005 mmol) in DMF;
yield: 42 mg (0.083 mmol, 83%); colourless oil; IR (neat,
ATR probe): n=3272, 2960, 1731 (C=O), 1447, 1355, 1306,
1306, 1197, 1163, 1132, 1022 cmÀ1
;
1H NMR (400 MHz,
3
CDCl3): d=1.29 (t, J=7.1 Hz, 3H), 1.49 (s, 3H), 1.98 (ddd,
2J=13.6 Hz, 3J=5.4 and 11.1 Hz, 1H), 2.21 (ddd, 2J=
3
13.6 Hz, J=5.3 and 11.2 Hz, 1H), 2.32 (s, 1H), 2.45 (ddd,
2J=16.4 Hz, 3J=5.4 and 11.1 Hz, 1H), 2.60 (ddd, 2J=
3
3
16.4 Hz, J=5.3 and 11.2 Hz, 1H), 3.68 (s, 3H), 4.23 (q, J=
7.1 Hz, 2H); 13C NMR (100 MHz, CDCl3): d=14.1, 25.7,
30.3, 34.5, 42.3, 51.7, 61.8, 71.9, 84.0, 172.5, 173.3; HR-MS
(ESI): m/z=235.0956, calcd. for C11H16O4Na [(M+Na)+]:
235.0946.
1-Ethyl 5-methyl 2-ethynyl-2-benzylpentanedioate (6bb):
From allene 5b (20.2 mg, 0.1 mmol), methyl acrylate 2b
(0.027 mL, 0.3 mmol) and MeSO2Na (0.9 mg, 0.005 mmol) in
DMF; yield: 16.3 mg (0.057 mmol, 57%); colourless oil; IR
(neat, ATR probe): n=3283, 2953, 1729 (C=O), 1496, 1438,
1
1174, 1147, 1087, 920 cmÀ1; H NMR (400 MHz, CDCl3): d=
1.22 (t, 3J=7.1 Hz, 3H), 1.26–1.34 (m, 1H), 1.45–1.66 (m,
4H), 1.74 (dt, J=4.5 and 12.5 Hz, 1H), 1.99 (dt, J=4.1 and
12.9 Hz, 1H), 2.16 (dt, J=4.4 and 12.9 Hz, 1H), 2.33 (s,
1H), 2.45 (m, 3H), 3.10 (dt, J=4.4 and 12.9 Hz, 1H), 3.34
1369, 1222, 1172, 1086, 1017 cmÀ1
CDCl3): d=1.20 (t, J=7.1 Hz, 3H), 2.02 (ddd, J=13.2 Hz,
3J=4.8 and 11.5 Hz, 1H), 2.28 (ddd, 2J=13.2 Hz, 3J=5.1
and 11.5 Hz, 1H), 2.38 (ddd, 2J=16.2 Hz, 3J=5.1 and
;
1H NMR (400 MHz,
3
2
3
2
3
(dt, J=4.1 and 12.9 Hz, 1H), 3.98 (t, J=6.4 Hz, 2H), 4.07–
11.5 Hz, 1H), 2.41 (s, 1H), 2.63 (ddd, J=16.2 Hz, J=5.1
and 11.5 Hz, 1H), 3.00 and 3.14 (AB, 2JAB =13.2 Hz, 1H
4.20 (m, 2H), 7.33–7.35 (m, 2H), 7.56–7.60 (m, 2H), 7.65–
7.70 (m, 1H), 7.75–7.77 (m, 2H), 7.88–7.91 (m, 2H);
13C NMR (100 MHz, CDCl3): d=14.1, 21.1, 21.6, 28.6, 31.2,
38.3, 46.8, 52.8, 62.2, 69.8, 74.2, 81.5, 127.9 (ꢅ2), 128.0 (ꢅ2),
129.4 (ꢅ2), 129.9 (ꢅ2), 133.0, 133.9, 138.9, 144.8, 170.9; HR-
MS (ESI): m/z=529.1339, calcd. for C25H30O7S2Na [(M+
Na)+]: 529.1331.
Ethyl 2-methyl-2-(2-cyanoethyl)but-3-ynoate (6aa): From
allene 5a (12.6 mg, 0.1 mmol), acrylonitrile 2a (0.02 mL,
0.3 mmol) and PhSO2Na (0.9 mg, 0.005 mmol) in DMF;
yield: 5.9 mg (0.033 mmol, 33%); colourless oil; IR (neat,
ATR probe): n=3281, 2986, 2250, 1731 (C=O), 1450, 1380,
3
each), 4.11 (q, J=7.1 Hz, 2H), 7.26 (s like, 5H); 13C NMR
(100 MHz, CDCl3): d=14.0, 30.3, 33.7, 45.1, 49.0, 51.7, 61.8,
74.7, 82.5, 127.2, 128.0 (ꢅ2), 130.3 (ꢅ2), 135.8, 171.5, 173.2;
HR-MS (ESI): m/z=311.1245, calcd. for C17H20O4Na [(M+
Na)+]: 311.1259.
5-(Ethoxy)dihydro-4-[1-benzyl-1-(ethoxycarbonyl)ethy-
nyl]furan-2(3H)-one (6bm): From allene 5b (20.2 mg,
0.1 mmol), 5-ethoxyfuranone 2m (12.8 mg, 0.1 mmol) and
PhSO2Na (0.9 mg, 0.005 mmol) in DMF as a mixture of two
diastereoisomers in a 1:1 ratio; yield: 20 mg (0.06 mmol,
60%); colourless oil; IR (neat, ATR probe): n=3279, 2981,
2934, 1785 (C=O), 1732 (C=O), 1455, 1171, 1116, 1038,
1251, 1198, 1125, 1019, 860 cmÀ1
;
1H NMR (400 MHz,
3
CDCl3): d=1.31 (t, J=7.1 Hz, 3H), 1.53 (s, 3H), 1.96 (ddd,
957 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.13 (t, 3J=
2J=13.5 Hz, 3J=5.6 and 10.3 Hz, 1H), 2.29 (ddd, 2J=
7.1 Hz, 1.5H), 1.21 (t, J=7.1 Hz, 1.5H), 1.22 (t, J=7.1 Hz,
3
3
3
3
3
13.5 Hz, J=5.8 and 10.5 Hz, 1H), 2.39 (s, 1H), 2.51 (ddd,
1.5H), 1.29 (t, J=7.1 Hz, 1.5H), 2.51 (s, 1H), 2.58 (dd, J=
6.8 Hz and 2J=18.1 Hz, 0.5H), 2.72–2.83 (m, 1.5H), 2.87–
2.98 (m, 1.5H), 3.06–3.21 (m, 1.5H), 3.54–3.62 (m, 0.5H),
3.66–3.74 (m, 0.5H), 3.81–3.89 (m, 0.5H), 3.90–3.98 (m,
2J=16.6 Hz, 3J=5.6 and 10.5 Hz, 1H), 2.60 (ddd, 2J=
3
3
16.6 Hz, J=5.8 and 10.3 Hz, 1H), 4.23 (q, J=7.1 Hz, 2H);
13C NMR (100 MHz, CDCl3): d=13.7, 14.0, 25.9, 35.0, 42.2,
62.2, 73.0, 82.7, 119.1, 171.6; HR-MS (ESI): m/z=202.0849,
calcd. for C10H13NO2Na [(M+Na)+]: 202.0844.
3
0.5H), 4.04–4.09 (m, 1H), 4.10–4.18 (m, 1H), 5.45 (d, J=
3
3.6 Hz, 0.5H), 5.64 (d, J=3.7 Hz, 0.5H), 7.18–7.27 (m, 5H);
Ethyl 2-benzyl-2-(2-cyanoethyl)but-3-ynoate (6ba): From
allene 5b (20.2 mg, 0.1 mmol), acrylonitrile 2a (0.02 mL,
0.3 mmol) and PhSO2Na (0.9 mg, 0.005 mmol) in DMF;
yield: 12.2 mg (0.048 mmol, 48%); colourless oil; IR (neat,
13C NMR (100 MHz, CDCl3): d=13.87 (ꢅ0.5), 13.93 (ꢅ0.5),
14.9 (ꢅ0.5), 15.0 (ꢅ0.5), 30.9 (ꢅ0.5), 31.6 (ꢅ0.5), 42.8 (ꢅ0.5),
43.2 (ꢅ0.5), 47.8 (ꢅ0.5), 48.5 (ꢅ0.5), 51.2 (ꢅ0.5), 51.5 (ꢅ0.5),
62.2 (ꢅ0.5), 62.3 (ꢅ0.5), 65.9 (ꢅ0.5), 66.0 (ꢅ0.5), 76.4 (ꢅ0.5),
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76.9 (ꢅ0.5), 79.6 (ꢅ0.5), 80.1 (ꢅ0.5), 105.5 (ꢅ0.5), 105.8 (ꢅ
0.5), 127.5, 128.2 (ꢅ2), 130.1, 130.1, 134.8 (ꢅ0.5), 134.9 (ꢅ
0.5), 169.7 (ꢅ0.5), 169.8 (ꢅ0.5), 174.27 (ꢅ0.5), 174.29 (ꢅ0.5);
HR-MS (ESI): m/z=353.1367, calcd. for C19H22O5Na [(M+
Na)+]: 353.1365.
Liu, G. B. Hammond, Eur. J. Org. Chem. 2010, 6855–
6862.
[8] For a recent review dedicated to compounds with
sulfur-containing quaternary carbon centres, see: J.-S.
Yu, H.-M. Huang, P.-G. Ding, X.-S. Hu, F. Zhou, J.
Zhou, ACS Catal. 2016, 6, 5319–5344.
[9] For a recent review dedicated to sulfinates, see: J. Aziz,
S. Messaoudi, M. Alami, A. Hamze, Org. Biomol.
Chem. 2014, 12, 9743–9759.
Acknowledgements
[10] For recent approaches to alkynes, see: a) W. Liu, Z.
Chen, L. Li, H. Wang, C.-J. Li, Chem. Eur. J. 2016, 22,
5888–5893; b) M. Zhang, T. Jia, C. Y. Wang, P. J. Walsh,
J. Am. Chem. Soc. 2015, 137, 10346–10350; c) H. Y.
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Org. Chem. 2015, 80, 8748–8757.
We acknowledge financial support from Region Normandie
(CRUNCh network), CNRS, EFRD and Labex SynOrg
(ANR-11-LABX-0029). This work has been also partially
supported by INSA Rouen and Rouen University. We wish to
thank Dr. Norbert Hoffmann (University of Reims) for a gen-
erous gift of the 5-alkoxyfuranones 2g and 2m.
[11] a) A. Padwa, S. S. Murphree, Z. Ni, S. H. Watterson, J.
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M. Seifi, Lett. Org. Chem. 2015, 12, 271–276; b) S.-Y.
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[14] S6 is an alternative catalyst, but is not commercially
available.
[15] F. Wudl, D. A. Lightner, D. J. Cram, J. Am. Chem. Soc.
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1
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on both C=C bonds of the Michael acceptor, was de-
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[19] The two diastereoisomers produced are probably epi-
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and the Supporting Information for further details.
[20] CCDC 1489261 (1g), CCDC 1489260 (3aa), CCDC
1489263 (3ag), CCDC 1489262 (7) and CCDC 1489259
(22) contain the supplementary crystallographic data
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charge from The Cambridge Crystallographic Data
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12 Unique Reactivity of a-Substituted Electron-Deficient
Allenes using Sulfinate Salts as Lewis Base Organocatalysts
Adv. Synth. Catal. 2016, 358, 1 – 12
Thomas Martzel, Jean-FranÅois Lohier,
Annie-Claude Gaumont, Jean-FranÅois Briꢀre,
Stꢁphane Perrio*
Adv. Synth. Catal. 0000, 000, 0 – 0
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ꢃ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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