Synthesis of alkynes from vinyl triflates using tetrabutylammonium fluoride

Article abstract of DOI:10.1248/cpb.c15-00146

A convenient method for the preparation of alkynes and alkynyl esters from ketones and β-keto esters is described which involves the formation of vinyl triflates, followed by elimination with tetrabutylammonium fluoride trihydrate, to give alkynes. Unlike established elimination methods, the method requires neither a strong base nor anhydrous conditions.

Full text of DOI:10.1248/cpb.c15-00146

Vol. 63, No. 5
Chem. Pharm. Bull. 63, 393–396 (2015)
393
Note
Synthesis of Alkynes from Vinyl Triflates Using Tetrabutylammonium
Fluoride
Masaru Okutani and Yuji Mori*
Faculty of Pharmacy, Meijo University; 150 Yagotoyama, Tempaku-ku, Nagoya 468–8503, Japan.
Received February 16, 2015; accepted March 9, 2015
A convenient method for the preparation of alkynes and alkynyl esters from ketones and β-keto esters is
described which involves the formation of vinyl triflates, followed by elimination with tetrabutylammonium
fluoride trihydrate, to give alkynes. Unlike established elimination methods, the method requires neither a
strong base nor anhydrous conditions.
Key wordsꢀ tetrabutylammoniumꢀfluoride;ꢀvinylꢀtriflate;ꢀelimination;ꢀalkyne
Tetrabutylammoniumꢀ fluorideꢀ (TBAF)ꢀ isꢀ widelyꢀ usedꢀ forꢀ amountꢀofꢀbaseꢀtoꢀ3.0ꢀequivꢀdrasticallyꢀshortenedꢀtheꢀreactionꢀ
organicꢀ synthesisꢀ inꢀ aꢀ rangeꢀ ofꢀ fluoride-assistedꢀ reactions,ꢀ timeꢀ fromꢀ 18ꢀhꢀ toꢀ 10ꢀminꢀ whileꢀ maintainingꢀ theꢀ highꢀ yieldꢀ
suchꢀ asꢀ deprotectionꢀ ofꢀ silylꢀ ethers,ꢀ desilylation,ꢀ andꢀ fluo- (Tableꢀ 1,ꢀ entryꢀ 3).ꢀ Theseꢀ optimizedꢀ reactionꢀ conditionsꢀ wereꢀ
rination.ꢀ TBAFꢀ canꢀ alsoꢀ actꢀ asꢀ aꢀ mildꢀ base1) in a variety of adopted for further study.
base-catalyzed,ꢀ aldol-typeꢀ condensationꢀ reactions2–4) and
Theꢀ eliminationꢀ reactionsꢀ ofꢀ acyclicꢀ vinylꢀ triflatesꢀ 2b–2d
Michael-typeꢀ reactions.5–7)ꢀ Weꢀ haveꢀ reportedꢀ thatꢀ TBAFꢀ canꢀ are usually completed in 20min to give the corresponding ter-
beꢀemployedꢀasꢀaꢀbaseꢀinꢀtheꢀanti-eliminationꢀreactionꢀofꢀvinylꢀ minal alkynes in good yields (Table 2, entries 1 to 3). Macro-
bromides to obtain the corresponding alkynes.8,9) The salient cyclic (Z)-vinylꢀtriflateꢀ2e18,31) also undergoes elimination, but
feature of this elimination is that dehydrobromination is ef- requiresꢀaꢀlongerꢀreactionꢀtimeꢀ(1ꢀh)ꢀtoꢀaffordꢀalkyneꢀ3e. This
ficientlyꢀbroughtꢀaboutꢀbyꢀtheꢀcommerciallyꢀavailableꢀhydratedꢀ reaction also affords the corresponding allene in 7% yield,
TBAFꢀ (TBAF·3H2O); further, in contrast to conventional whichꢀ mayꢀ ariseꢀ fromꢀ theꢀ E-isomerꢀ ofꢀ theꢀ startingꢀ materialꢀ
methods,ꢀ whichꢀ requireꢀ strongꢀ basesꢀ suchꢀ asꢀ t-BuOK,10–12) (Tableꢀ2,ꢀentryꢀ4).ꢀNotably,ꢀtheꢀLDA-inducedꢀeliminationꢀreac-
alkali hydrides,13–15) and alkali metal amides16,17)ꢀ asꢀ wellꢀ asꢀ tion of a 10:1 E/Zꢀmixtureꢀofꢀ2e has been reported to afford a
strictlyꢀ anhydrousꢀ conditions,ꢀ ourꢀ moisture-insensitiveꢀ proto- 93ꢀ:ꢀ7ꢀmixtureꢀofꢀtheꢀalkyneꢀandꢀalleneꢀinꢀ95%ꢀyield,ꢀwhileꢀanꢀ
col is very practical.
11:1 E/Zꢀmixtureꢀofꢀaꢀvinylꢀphosphateꢀderivativeꢀcorrespond-
Inꢀ thisꢀ work,ꢀ weꢀ haveꢀ extendedꢀ theꢀ scopeꢀ ofꢀ theꢀ hydratedꢀ ing to 2e affords the allene in 75% yield.32)
TBAF-inducedꢀeliminationꢀreactionꢀtoꢀvinylꢀtriflatesꢀ2,ꢀwhichꢀ
Theꢀsuccessꢀofꢀthisꢀreactionꢀpromptedꢀusꢀtoꢀextendꢀtheꢀpro-
are more reactive than vinyl bromides and can be readily pre- cedureꢀtoꢀvinylꢀtriflatesꢀ5 derived from β-ketoꢀestersꢀ4 (Table
pared from ketones 1 (Chart 1). Several different procedures 3). The transformation of β-ketoꢀ estersꢀ toꢀ conjugatedꢀ alkynylꢀ
forꢀconversionꢀofꢀvinylꢀtriflatesꢀtoꢀalkynesꢀhaveꢀbeenꢀreported;ꢀ esters viaꢀaꢀvinylꢀtriflateꢀhasꢀbeenꢀreportedꢀbyꢀBrummondꢀ et
however,ꢀasꢀwithꢀvinylꢀbromides,ꢀmostꢀofꢀtheꢀtriflatesꢀrequireꢀ al.18) and Maity and Lepore.23)ꢀ Althoughꢀ theirꢀ procedureꢀ isꢀ
strong bases and anhydrous conditions,18–24) or prolonged heat- usefulꢀforꢀ2-alkynoateꢀsynthesis,ꢀitꢀrequiresꢀanhydrousꢀcondi-
ingꢀwithꢀweakꢀbasesꢀatꢀelevatedꢀtemperatures.25–27)ꢀTheꢀTBAF- tionsꢀ andꢀ theꢀ useꢀ ofꢀ LDAꢀ orꢀ lithiumꢀ bis(trimethylsilyl)ꢀamideꢀ
inducedꢀ eliminationꢀ ofꢀ vinylꢀ triflatesꢀ isꢀ rareꢀ inꢀ theꢀ literature,ꢀ (LiHMDS)ꢀ asꢀ theꢀ base.ꢀ Flemingꢀ andꢀ Ramaraoꢀ haveꢀ dem-
andꢀonlyꢀtwoꢀexamplesꢀofꢀitsꢀuseꢀwereꢀfound.28,29)
onstratedꢀ aꢀ decarboxylativeꢀ eliminationꢀ ofꢀ triflicꢀ acidꢀ fromꢀ
Vinylꢀ triflatesꢀ 2ꢀ wereꢀ preparedꢀ fromꢀ theꢀ correspond- vinylꢀtriflateꢀ5 to form terminal acetylenes in the presence of
ing ketones 1 in 50–80% yields by the established pro-
cedureꢀ usingꢀ lithiumꢀ diisopropylamideꢀ (LDA)ꢀ andꢀ N-(2- Table 1. Elimination Reaction of 2aꢀMediatedꢀbyꢀTBAF·3H2O
pyridiyl)ꢀtriflimide18,30) under kinetically controlled conditions.
Initialꢀ experimentsꢀ wereꢀ performedꢀ usingꢀ vinylꢀ triflateꢀ 2a to
establish reaction conditions (Table 1). Treatment of 2aꢀ withꢀ
1.1ꢀ equivꢀ ofꢀ TBAF·3H2O in N,N-dimethylformamideꢀ (DMF)ꢀ
at room temperature resulted in incomplete conversion of 2a
Entry
TBAF·3H2Oꢀ(equiv)
Time
Yield (%)
to terminal acetylene 3a after 22h, and 11% of the starting
materialꢀ wasꢀ recoveredꢀ (Tableꢀ 1,ꢀ entryꢀ 1).ꢀ Reactionꢀ withꢀ 2.0ꢀ
equivꢀofꢀtheꢀbaseꢀledꢀtoꢀcompleteꢀelimination,ꢀresultingꢀinꢀ91%ꢀ
yield of the product (Table 1, entry 2). Further increase in the
1
2
3
1.1
2.0
3.0
2h
18h
78 (+11% of sm)
91
10min
92
Chartꢀ 1.ꢀ PreparationꢀofꢀAlkynesꢀfromꢀKetonesꢀviaꢀVinylꢀTriflates
*ꢀToꢀwhomꢀcorrespondenceꢀshouldꢀbeꢀaddressed.ꢀ e-mail:ꢀmori@meijo-u.ac.jp
© 2015 The Pharmaceutical Society of Japan

394
Chem. Pharm. Bull.
Vol. 63, No. 5 (2015)
Tableꢀ 2.ꢀ EliminationꢀReactionꢀofꢀVinylꢀTriflatesꢀ2b–eꢀwithꢀTBAF·3H2O
Entry
1
Vinylꢀtriflate
Time (min)
20
Product
Yield (%)
94
2
3
20
15
95
76
84
4
60
(+7% allene)
Table 3. Elimination Reaction of (Z)-3-Triflyloxy-2-enoatesꢀ5a–cꢀwithꢀTBAF·3H2O
Entry
1
Vinylꢀtriflate
Time
20
Product
Yield (%)
93
2
3
10
25
93
90
trifluoroaceticꢀ acid,ꢀ followedꢀ byꢀ heatingꢀ withꢀ K2CO3 in ace- thatꢀ achievedꢀ inꢀ theꢀ one-potꢀ reactionꢀ reportedꢀ byꢀ Maityꢀ andꢀ
tone.33,34)ꢀHence,ꢀinvestigationꢀofꢀtheꢀreactionꢀofꢀvinylꢀtriflatesꢀ Lepore.23)ꢀ inꢀ whichꢀ β-ketoꢀ estersꢀ wereꢀ treatedꢀ withꢀ LiHMDSꢀ
5ꢀwithꢀhydratedꢀTBAFꢀcouldꢀprovideꢀaꢀconvenientꢀalternativeꢀ andꢀ triflicꢀ anhydrideꢀ (Tf2O) at −78°C.ꢀ However,ꢀ theꢀ reactionꢀ
to established methods of alkynoate synthesis.
conditions described here are very mild.
Severalꢀmethodsꢀforꢀtheꢀtriflationꢀofꢀβ-ketoꢀesters,ꢀinꢀwhichꢀ
Inꢀconclusion,ꢀweꢀhaveꢀdemonstratedꢀanꢀefficientꢀmethodꢀforꢀ
the stereochemical outcome of the reaction strongly depends theꢀ synthesisꢀ ofꢀ terminalꢀ alkynesꢀ andꢀ 2-alkynylꢀ estersꢀ fromꢀ
onꢀ theꢀ triflatingꢀ reagentꢀ andꢀ solvent,ꢀ haveꢀ beenꢀ reported.35) vinylꢀ triflatesꢀ usingꢀ hydratedꢀ TBAFꢀ toꢀ promoteꢀ elimination,ꢀ
Ourꢀ previousꢀ studyꢀ hasꢀ shownꢀ thatꢀ theꢀ TBAF-inducedꢀ elimi- inꢀwhichꢀTBAFꢀservesꢀasꢀaꢀmildꢀbaseꢀtoꢀeliminateꢀtriflicꢀacidꢀ
nation proceeds via an anti-transitionꢀ state.9) Therefore, the fromꢀ vinylꢀ triflatesꢀ atꢀ roomꢀ temperature.ꢀ Thisꢀ methodꢀ isꢀ aꢀ
requisiteꢀsubstratesꢀshouldꢀbeꢀ(Z)-vinylꢀtriflatesꢀ5.ꢀTheseꢀwereꢀ robustꢀandꢀmoisture-insensitiveꢀalternativeꢀtoꢀexistingꢀmethodsꢀ
prepared stereoselectively according to the procedure reported of alkyne synthesis from ketones and β-ketoꢀesters.
by Pale and colleagues.36) Elimination reactions of 5a–cꢀwithꢀ
3.0ꢀ equivꢀ ofꢀ TBAF·3H2Oꢀ wereꢀ carriedꢀ outꢀ inꢀ DMFꢀ atꢀ roomꢀ
temperature,ꢀ andꢀ theꢀ resultsꢀ areꢀ summarizedꢀ inꢀ Tableꢀ 3.ꢀ Asꢀ
Experimental
Generalꢀ ꢀAllꢀ air-ꢀ andꢀ moisture-sensitiveꢀ reactionsꢀ wereꢀ
expected,ꢀ hydratedꢀ TBAFꢀ promotedꢀ theꢀ eliminationꢀ reactionꢀ carried out under an argon atmosphere in dry, freshly distilled
of 5ꢀ withinꢀ 30ꢀminꢀ toꢀ giveꢀ conjugatedꢀ alkyneꢀ estersꢀ 6a–6c solvents. The term “dried” refers to the drying of an organic
inꢀ highꢀ yields.ꢀ Theꢀ overallꢀ transformationꢀ wasꢀ similarꢀ toꢀ solution over MgSO4,ꢀfollowedꢀbyꢀfiltration.ꢀFlashꢀchromatog-

Vol. 63, No. 5 (2015)
Chem. Pharm. Bull.
395
raphyꢀ wasꢀ carriedꢀ outꢀ withꢀ silicaꢀ gelꢀ (spherical,ꢀ neutral,ꢀ par- 2.46ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 1.83ꢀ (2H,ꢀ m).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ
ticleꢀsizeꢀ40–50ꢀµm).ꢀIRꢀspectraꢀwereꢀrecordedꢀinꢀCHCl3 solu- CDCl3) δ:ꢀ 156.5,ꢀ 144.1,ꢀ 128.6,ꢀ 127.8,ꢀ 127.0,ꢀ 118.8ꢀ (q,ꢀ
tionꢀ onꢀ aꢀ JASCOꢀ FTIR-420ꢀ spectrometer.ꢀ 1H-ꢀ andꢀ 13C-NMRꢀ J=318ꢀHz),ꢀ104.4,ꢀ86.5,ꢀ61.7,ꢀ30.9,ꢀ26.6.ꢀIRꢀ(CHCl3) cm−1: 1671,
spectraꢀwereꢀrecordedꢀonꢀaꢀJEOLꢀA-400ꢀspectrometer.ꢀChemi- 1491,ꢀ 1448,ꢀ 1415,ꢀ 1145.ꢀ HR-EI-MSꢀ m/z: 476.1296 (Calcd for
cal shifts are reported in ppm relative to an internal TMS C25H23F3 O4S: 476.1269).
1
standard (δ 0.00ppm) for H-NMRꢀspectra,ꢀandꢀtoꢀtheꢀsolventꢀ
1-(Naphthalen-2-yl)vinyl Trifluoromethanesulfonate (2d)
signals (δ 77.0ppm for CDCl3) for 13C-NMRꢀ spectra.ꢀ High- 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:ꢀ 8.03ꢀ (1H,ꢀ d,ꢀ J=1.9ꢀHz),ꢀ
resolutionꢀ electron-impactꢀ massꢀ spectraꢀ (HR-EI-MS)ꢀ wereꢀ 7.92–7.83ꢀ (3H,ꢀ m),ꢀ 7.61–7.52ꢀ (3H,ꢀ m),ꢀ 5.73ꢀ (1H,ꢀ d,ꢀ J=3.9ꢀHz),ꢀ
recordedꢀonꢀJEOLꢀJMS-700ꢀmassꢀspectrometer.
5.47ꢀ (1H,ꢀ d,ꢀ J=3.9ꢀHz).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) δ:
General Procedure for Triflation of Ketones30)ꢀ ꢀA ꢀ s o - 153.5, 133.85, 132.81, 129.2, 128.8, 128.7, 127.7, 127.5, 127.0,
lution of ketone 1ꢀ (4.0ꢀmmol,ꢀ 1.0ꢀ equiv)ꢀ inꢀ tetrahydrofuranꢀ 125.2,ꢀ 122.1,ꢀ 118.8ꢀ (q,ꢀ J=318ꢀHz),ꢀ 104.5.ꢀ IRꢀ (CHCl3) cm−1:
(THF)ꢀ (10ꢀmL)ꢀ wasꢀ addedꢀ dropwiseꢀ toꢀ aꢀ stirringꢀ solutionꢀ ofꢀ 1672,ꢀ 1595,ꢀ 1410,ꢀ 1140.ꢀ HR-EI-MSꢀ m/z: 302.0246 (Calcd for
LDAꢀ (1.5ꢀ equiv)ꢀ inꢀ THFꢀ (3ꢀmL)ꢀ atꢀ −80°C.ꢀ Afterꢀ stirringꢀ atꢀ C13H9F3 O3S: 302.0224).
−80°C for 2h, a solution of N-(2-pyridyl)ꢀtriflimideꢀ(1.2ꢀequiv)ꢀ
(Z)-Cyclododec-1-en-1-yl Trifluoromethanesulfonate (2e)18,31)
inꢀ THFꢀ (9ꢀmL)ꢀ wasꢀ added.ꢀ Theꢀ reactionꢀ mixtureꢀ wasꢀ stirredꢀ 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:ꢀ 5.37ꢀ (1H,ꢀ t,ꢀ J=8.3ꢀHz),ꢀ 2.41ꢀ
forꢀ1ꢀhꢀatꢀtheꢀsameꢀtemperatureꢀandꢀthenꢀallowedꢀtoꢀwarmꢀtoꢀ (2H,ꢀ t,ꢀ J=6.3ꢀHz),ꢀ 2,25ꢀ (2H,ꢀ m),ꢀ 1.55–1.25ꢀ (16H).ꢀ 13C-NMRꢀ
0°C,ꢀ followedꢀ byꢀ stirringꢀ forꢀ 2ꢀh.ꢀ Theꢀ reactionꢀ wasꢀ quenchedꢀ (100ꢀMHz,ꢀ CDCl3) δ:ꢀ 184.6,ꢀ 123.8,ꢀ 118.4ꢀ (q,ꢀ J=319ꢀHz),ꢀ 33.2,ꢀ
withꢀsaturatedꢀaqueousꢀNH4Clꢀsolution,ꢀandꢀtheꢀreactionꢀmix- 26.2,ꢀ25.7,ꢀ25.4,ꢀ25.3,ꢀ25.2,ꢀ24.5,ꢀ24.4,ꢀ24.2,ꢀ22.9.ꢀIRꢀ(CHCl3)
tureꢀwasꢀextractedꢀwithꢀdiethylꢀether.ꢀTheꢀextractꢀwasꢀwashedꢀ cm−1:ꢀ1692,ꢀ1411,ꢀ1221,ꢀ1142.ꢀHR-EI-MSꢀm/z: 314.1160 (Calcd
withꢀ waterꢀ andꢀ brine,ꢀ dried,ꢀ andꢀ concentratedꢀ underꢀ reducedꢀ for C13H21F3 O3S: 314.1163). 1H-NMRꢀ dataꢀ ofꢀ theꢀ contami-
pressure.ꢀ Purificationꢀ ofꢀ theꢀ residueꢀ byꢀ flashꢀ chromatographyꢀ nated E-isomerꢀ (8%)ꢀ δ:ꢀ 5.48ꢀ (1H,ꢀ t,ꢀ J=8.3ꢀHz),ꢀ 2.45ꢀ (2H,ꢀ t,ꢀ
(1–5%ꢀ ethylꢀ acetateꢀ inꢀ hexane)ꢀ affordedꢀ vinylꢀ triflateꢀ 2 in J=6.8ꢀHz),ꢀ2.15ꢀ(2H,ꢀdt,ꢀJ=8.3,ꢀ6.8ꢀHz),ꢀ1.70–1.25ꢀ(16H).
50–85% yield.
Tridec-1-yne (3a) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ: 2.18
General Procedure for Triflation of β-Keto Esters36) To (2H,ꢀ dt,ꢀ J=7.3,ꢀ 2.7ꢀHz),ꢀ 1.93ꢀ (1H,ꢀ t,ꢀ J=2.7ꢀHz),ꢀ 1.52ꢀ (2H,ꢀ
a suspension of β-ketoꢀesterꢀ4ꢀ(3.0ꢀmmol,ꢀ1.0ꢀequiv)ꢀandꢀLiOTfꢀ m),ꢀ 1.40–1.25ꢀ (16H,ꢀ m),ꢀ 0.88ꢀ (3H,ꢀ t,ꢀ J=6.8ꢀHz).ꢀ 13C-NMRꢀ
(2.0ꢀ equiv)ꢀ inꢀ CH2Cl2ꢀ (30ꢀmL)ꢀ atꢀ 0°Cꢀ wasꢀ addedꢀ Et3N (1.1 (100ꢀMHz,ꢀ CDCl3) δ: 84.8, 68.0, 31.9, 29.7, 29.6, 29.5, 29.3,
equiv).ꢀAfterꢀstirringꢀatꢀ0°Cꢀforꢀ20ꢀmin,ꢀTf2Oꢀ(1.1ꢀequiv)ꢀwasꢀ 29.1,ꢀ28.7,ꢀ28.5,ꢀ22.7,ꢀ18.4,ꢀ14.1.ꢀIRꢀ(CHCl3) cm−1: 3307, 2109,
added,ꢀandꢀtheꢀreactionꢀmixtureꢀwasꢀstirredꢀforꢀ1ꢀhꢀatꢀthisꢀtem- 1467.ꢀHR-EI-MSꢀm/z: 180.1875 (Calcd for C13H24: 180.1878).
perature.ꢀ Theꢀ reactionꢀ wasꢀ quenchedꢀ withꢀ saturatedꢀ aqueousꢀ
Hex-5-yn-1-ylbenzene (3b) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3)
NH4Clꢀ solution,ꢀ andꢀ theꢀ reactionꢀ mixtureꢀ wasꢀ extractedꢀ withꢀ δ:ꢀ 7.30–7.16ꢀ (5H,ꢀ m),ꢀ 2.63ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 2.20ꢀ (2H,ꢀ dt,ꢀ
CH2Cl2.ꢀTheꢀextractꢀwasꢀwashedꢀwithꢀwaterꢀandꢀbrine,ꢀdried,ꢀ J=6.8,ꢀ2.4ꢀHz),ꢀ1.94ꢀ(1H,ꢀt,ꢀJ=2.4ꢀHz),ꢀ1.75ꢀ(2H,ꢀm),ꢀ1.58ꢀ(2H,ꢀ
andꢀ concentratedꢀ underꢀ reducedꢀ pressure.ꢀ Purificationꢀ ofꢀ theꢀ m). 13C-NMRꢀ(100ꢀMHz,ꢀCDCl3) δ: 142.2, 128.4, 128.3, 125.7,
residueꢀbyꢀflashꢀchromatographyꢀ(5–15%ꢀethylꢀacetateꢀinꢀhex- 84.4,ꢀ68.3,ꢀ35.4,ꢀ30.4,ꢀ28.0,ꢀ18.3.ꢀIRꢀ(CHCl3) cm−1: 3308, 2118,
ane)ꢀaffordedꢀvinylꢀtriflateꢀ5 in 65–82% yield.
1604,ꢀ1496,ꢀ1454.ꢀHR-EI-MSꢀm/z: 158.1083 (Calcd for C12H14:
General Procedure for Elimination Reaction of Vinyl 158.1096).
Triflates with TBAF·H2Oꢀ ꢀToꢀ aꢀ solutionꢀ ofꢀ vinylꢀ triflateꢀ
(Pent-4-yn-1-yloxy)triphenylmethane (3c) 1H-NMRꢀ(400ꢀMHz,ꢀ
2ꢀ (0.5ꢀmmol)ꢀ inꢀ DMFꢀ (2.5ꢀmL)ꢀ wasꢀ addedꢀ aꢀ 1ꢀM solution of CDCl3) δ:ꢀ7.48–7.20ꢀ(15H,ꢀm),ꢀ3.16ꢀ(2H,ꢀt,ꢀJ=5.9ꢀHz),ꢀ2.34ꢀ(2H,ꢀ
TBAF·3H2Oꢀ inꢀ DMFꢀ (1.5ꢀmmol).ꢀ Theꢀ reactionꢀ mixtureꢀ wasꢀ t, J=7.3ꢀHz),ꢀ 1.82ꢀ (2H,ꢀ m),ꢀ 1.88ꢀ (1H,ꢀ t,ꢀ J=2.4ꢀHz).ꢀ 13C-NMRꢀ
stirredꢀ forꢀ 15–60ꢀminꢀ andꢀ extractedꢀ withꢀ diethylꢀ ether.ꢀ Theꢀ (100ꢀMHz,ꢀ CDCl3) δ: 144.2, 128.7, 127.7, 126.9, 86.5, 84.1,
organicꢀ phaseꢀ wasꢀ washedꢀ withꢀ waterꢀ andꢀ brine,ꢀ dried,ꢀ andꢀ 68.4,ꢀ61.9,ꢀ29.2,ꢀ20.2.ꢀIRꢀ(CHCl3) cm−1: 3308, 2117, 1597, 1491,
concentratedꢀ underꢀ reducedꢀ pressure.ꢀ Purificationꢀ ofꢀ theꢀ resi- 1448.ꢀHR-EI-MSꢀm/z: 326.1667 (Calcd for C24H22O: 326.1671).
dueꢀbyꢀflashꢀchromatographyꢀ(hexaneꢀorꢀ1–5%ꢀethylꢀacetateꢀinꢀ
2-Ethynylnaphthalene (3d) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3)
hexane)ꢀaffordedꢀalkynesꢀ3.
δ:ꢀ8.03ꢀ(1H,ꢀs),ꢀ7.85–7.78ꢀ(3H,ꢀm),ꢀ7.54–7.48ꢀ(3H,ꢀm),ꢀ3.15ꢀ(1H,ꢀ
1
Tridec-1-en-2-yl Trifluoromethanesulfonate (2a) 1H-NMRꢀ s). The H-NMRꢀ spectrumꢀ ofꢀ 3dꢀ wasꢀ identicalꢀ withꢀ aꢀ refer-
(400ꢀMHz,ꢀ CDCl3) δ:ꢀ 5.09ꢀ (1H,ꢀ d,ꢀ J=3.4ꢀHz),ꢀ 4.92ꢀ (1H,ꢀ d,ꢀ enceꢀsampleꢀofꢀcommerciallyꢀavailableꢀ2-ethynylnaphthalene.
J=3.4ꢀHz),ꢀ2.33ꢀ(2H,ꢀt,ꢀJ=7.3ꢀHz),ꢀ1.55ꢀ(2H,ꢀm),ꢀ1.26ꢀ(16H,ꢀm),ꢀ
Cyclododecyne (3e) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:
0.88ꢀ (3H,ꢀ t,ꢀ J=6.8ꢀHz).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) δ: 157.1, 2,20–2.17ꢀ (4H,ꢀ m),ꢀ 1.58–1.51ꢀ (8H,ꢀ m),ꢀ 1.47–1.40ꢀ (8H,ꢀ m).ꢀ
118.4ꢀ (q,ꢀ J=318ꢀHz),ꢀ 103.9,ꢀ 33.8,ꢀ 31.9,ꢀ 29.5,ꢀ 29.43,ꢀ 29.41,ꢀ 29.3,ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) δ: 81.6, 25.7, 25.5, 24.9, 24.6,
29.2,ꢀ28.6,ꢀ25.9,ꢀ22.7,ꢀ14.0.ꢀIRꢀ(CHCl3) cm−1: 1670, 1416, 1140. 18.5.ꢀ IRꢀ (CHCl3) cm−1:ꢀ 1461,ꢀ 1447,ꢀ 1322.ꢀ HR-EI-MSꢀ m/z:
HR-EI-MSꢀm/z: 330.1462 (Calcd for C14H25F3 O3S: 330.1476).
6-Phenylhex-1-en-2-yl Trifluoromethanesulfonate (2b)
164.1531 (Calcd for C12H20: 164.1565).
1,2-Cyclododecadiene (Allene) 1H-NMRꢀ (400ꢀMHz,ꢀ
1H-NMRꢀ(400ꢀMHz,ꢀCDCl3) δ:ꢀ7.32–7.11ꢀ(5H,ꢀm),ꢀ5.09ꢀ(1H,ꢀd,ꢀ CDCl3) δ:ꢀ 4.92–4.84ꢀ (2H,ꢀ m),ꢀ 2.17–2.02ꢀ (4H,ꢀ m),ꢀ 1.53–1.37ꢀ
J=3.4ꢀHz),ꢀ4.90ꢀ(1H,ꢀdt,ꢀJ=3.4,ꢀ1.0ꢀHz),ꢀ2.64ꢀ(2H,ꢀm),ꢀ2.36ꢀ(2H,ꢀ (10H,ꢀ m),ꢀ 1.27–1.05ꢀ (4H,ꢀ m).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) δ:
t, J=6.8ꢀHz),ꢀ 1.79–1.55ꢀ (4H,ꢀ m).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) 206.6,ꢀ88.9,ꢀ27.0,ꢀ26.8,ꢀ26.1,ꢀ22.8,ꢀ21.6.ꢀIRꢀ(CHCl3) cm−1: 1956,
δ:ꢀ156.7,ꢀ142.2,ꢀ128.4,ꢀ128.3,ꢀ125.7,ꢀ118.6ꢀ(q,ꢀJ=317ꢀHz),ꢀ104.2,ꢀ 1460,ꢀ 1443,ꢀ 1328,ꢀ 1270.ꢀ HR-EI-MSꢀ m/z: 164.1548 (Calcd for
35.4,ꢀ 34.9,ꢀ 30.3,ꢀ 26.0.ꢀ IRꢀ (CHCl3) cm−1: 1671, 1604, 1498, C12H20: 164.1565).
1452,ꢀ1142.ꢀHR-EI-MSꢀm/z: 308.0688 (Calcd for C13H15F3 O3S:
308.0694).
(Z)-tert-Butyl 3-((Trifluoromethanesulfonyl)oxy)tetradec-
2-enoate (5a) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:ꢀ 5.66ꢀ (1H,ꢀ s),ꢀ
5-(Trityloxy)pent-1-en-2-yl Trifluoromethanesulfonate (2c) 2.34ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 1.51ꢀ (2H,ꢀ m),ꢀ 1.50ꢀ (9H,ꢀ s),ꢀ 1.31–1.25ꢀ
1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:ꢀ 7.47–7.22ꢀ (15H,ꢀ m),ꢀ 5.04ꢀ (1H,ꢀ (16H,ꢀm),ꢀ0.88ꢀ(3H,ꢀt,ꢀJ=6.8ꢀHz).ꢀ13C-NMRꢀ(100ꢀMHz,ꢀCDCl3)
d, J=3.4ꢀHz),ꢀ 4.86ꢀ (1H,ꢀ d,ꢀ J=3.4ꢀHz),ꢀ 3.13ꢀ (2H,ꢀ t,ꢀ J=6.8ꢀHz),ꢀ δ:ꢀ 161.8,ꢀ 157.6,ꢀ 118.3ꢀ (q,ꢀ J=319ꢀHz),ꢀ 113.3,ꢀ 82.3,ꢀ 34.2,ꢀ 31.9,ꢀ

396
Chem. Pharm. Bull.
(2004).
Vol. 63, No. 5 (2015)
29.54, 29.51, 29.33, 29.28, 29.1, 28.6, 27.9 (3×C), 25.8, 22.7,
14.1.ꢀIRꢀ(CHCl3) cm−1:ꢀ1721,ꢀ1676,ꢀ1428,ꢀ1149.ꢀHR-EI-MSꢀm/z:
374.1397 (Calcd for C15H25F3O5S [M−C4H8]+: 374.1375).
(Z)-tert-Butyl 5-Phenyl-3-((trifluoromethanesulfonyl)oxy)-
pent-2-enoate (5b) 1H-NMRꢀ(400ꢀMHz,ꢀCDCl3) δ: 7.34–7.16
(5H,ꢀ m),ꢀ 5.66ꢀ (1H,ꢀ t,ꢀ J=1.0ꢀHz),ꢀ 2.88ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 2.64ꢀ
(2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 1.49ꢀ (9H,ꢀ s).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3)
δ:ꢀ161.6,ꢀ156.2,ꢀ138.8,ꢀ128.8,ꢀ128.2,ꢀ126.8,ꢀ118.4ꢀ(q,ꢀJ=318ꢀHz),ꢀ
114.6, 82.5, 36.2, 32.2, 27.9 (3×C).ꢀ IRꢀ (CHCl3) cm−1: 1722,
1676,ꢀ 1497,ꢀ 1456,ꢀ 1428,ꢀ 1221,ꢀ 1149.ꢀ HR-EI-MSꢀ m/z: 324.0245
(Calcd for C12H11F3 O5S [M−C4H8]+: 324.0279).
ꢀ 5)ꢀ MatsumotoꢀK.,ꢀAngew. Chem. Int. Ed. Engl., 20, 770–771 (1981).
ꢀ 6)ꢀ Tárragaꢀ A.,ꢀ Molinaꢀ P.,ꢀ Lópezꢀ J.ꢀ L.,ꢀ Tetrahedron Lett., 41, 4895–
4899 (2000).
ꢀ 7)ꢀ SharmaꢀG.ꢀV.ꢀM.,ꢀReddyꢀV.ꢀG.,ꢀChanderꢀA.ꢀS.,ꢀReddyꢀK.ꢀR.,ꢀTetra-
hedron Asymmetry, 13, 21–24 (2002).
8) Okutani M., Mori Y., Tetrahedron Lett., 48, 6856–6859 (2007).
9) Okutani M., Mori Y., J. Org. Chem., 74, 442–444 (2009).
10)ꢀ Dulcèreꢀ J.ꢀ P.,ꢀ Mihoubiꢀ M.ꢀ N.,ꢀ Rodriguezꢀ J.,ꢀ J. Org. Chem., 58,
5709–5716 (1993).
11)ꢀ Ohnoꢀ H.,ꢀ Todaꢀ A.,ꢀ Fujiiꢀ N.,ꢀ Ibukaꢀ T.,ꢀ Tetrahedron Asymmetry, 9,
3929–3933 (1998).
12)ꢀ Weiꢀ L.-L.,ꢀ Mulderꢀ J.ꢀ A.,ꢀ Xiongꢀ H.,ꢀ Zificsakꢀ C.ꢀ A.,ꢀ Douglasꢀ C.ꢀ J.,ꢀ
HsungꢀR.ꢀP.,ꢀTetrahedron, 57, 459–466 (2001).
13)ꢀ Lütjensꢀ H.,ꢀ Nowotnyꢀ S.,ꢀ Knochelꢀ P.,ꢀ Tetrahedron Asymmetry, 6,
2675–2678 (1995).
14)ꢀ D’hoogheꢀ M.,ꢀ Vanꢀ Brabandtꢀ W.,ꢀ Deꢀ Kimpeꢀ N.,ꢀ J. Org. Chem., 69,
2703–2710 (2004).
15)ꢀ MyersꢀA.ꢀG.,ꢀSogiꢀM.,ꢀLewisꢀM.ꢀA.,ꢀArvedsonꢀS.ꢀP.,ꢀJ. Org. Chem.,
69, 2516–2525 (2004).
(Z)-tert-Butyl 7-(Benzyloxy)-3-((trifluoromethanesulfonyl)-
oxy)hept-2-enoate (5c) 1H-NMRꢀ (400ꢀMHz,ꢀ CDCl3) δ:
7.36–7.24ꢀ (5H,ꢀ m),ꢀ 5.66ꢀ (1H,ꢀ s),ꢀ 3.86ꢀ (2H,ꢀ t,ꢀ J=5.3ꢀHz),ꢀ 2.36ꢀ
(2H,ꢀm),ꢀ1.67–1.51ꢀ(4H,ꢀm),ꢀ1.50ꢀ(9H,ꢀs).ꢀ13C-NMRꢀ(100ꢀMHz,ꢀ
CDCl3) δ:ꢀ 161.8,ꢀ 156.4,ꢀ 138.3,ꢀ 128.3,ꢀ 127.6,ꢀ 127.5,ꢀ 118.3ꢀ (q,ꢀ
J=318ꢀHz),ꢀ 113.2,ꢀ 82.3,ꢀ 72.9,ꢀ 69.9,ꢀ 34.2,ꢀ 31.8,ꢀ 28.0ꢀ (3×C),
24.6.ꢀ IRꢀ (CHCl3) cm−1: 1722, 1676, 1496, 1451, 1425, 1230,
1147.ꢀ HR-EI-MSꢀ m/z: 382.0667 (Calcd for C15H17F3O6S [M−
C4H8]+: 382.0698).
16)ꢀ Ikeuchiꢀ Y.,ꢀ Taguchiꢀ T.,ꢀ Hanzawaꢀ Y.,ꢀ J. Org. Chem., 70, 756–759
(2005).
tert-Butyl Tetradec-2-ynoate (6a) 1H-NMRꢀ (400ꢀMHz,ꢀ
CDCl3) δ:ꢀ 2.29ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 1.56ꢀ (2H,ꢀ m),ꢀ 1.49ꢀ (9H,ꢀ
s),ꢀ 1.47–1.26ꢀ (16H,ꢀ m),ꢀ 0.88ꢀ (3H,ꢀ t,ꢀ J=6.8ꢀHz).ꢀ 13C-NMRꢀ
(100ꢀMHz,ꢀCDCl3) δ: 153.0, 87.1, 82.9, 74.4, 31.9, 29.6 (2×C),
29.4, 29.3, 29.0, 28.9, 28.0 (3×C), 27.6, 22.7, 18.6, 14.1; IR
(CHCl3) cm−1:ꢀ2235,ꢀ1699,ꢀ1457,ꢀ1370,ꢀ1284,ꢀ1159.ꢀHR-EI-MSꢀ
m/z: 280.2416 (Calcd for C18H32O2: 280.2402).
17)ꢀ MaꢀY.,ꢀRamirezꢀA.,ꢀSinghꢀK.ꢀJ.,ꢀKeresztesꢀI.,ꢀCollumꢀD.ꢀB.,ꢀJ. Am.
Chem. Soc., 128, 15399–15404 (2006).
18)ꢀ BrummondꢀK.ꢀM.,ꢀGesenbergꢀK.ꢀD.,ꢀKentꢀJ.ꢀL.,ꢀKerekesꢀA.ꢀD.,ꢀTet-
rahedron Lett., 39, 8613–8616 (1998).
19)ꢀ KatritzkyꢀA.ꢀR.,ꢀZhangꢀS.,ꢀFangꢀY.,ꢀOrg. Lett., 2, 3789–3791 (2000).
20)ꢀ Pérez-GarcíaꢀX.,ꢀRumboꢀA.,ꢀLarribaꢀM.ꢀJ.,ꢀOrdóñezꢀP.,ꢀMuñozꢀA.,ꢀ
MouriñoꢀA.,ꢀOrg. Lett., 5, 4033–4036 (2003).
21)ꢀ Asanoꢀ M.,ꢀ Inoueꢀ M.,ꢀ Watanabeꢀ K.,ꢀ Abeꢀ H.,ꢀ Katohꢀ T.,ꢀ J. Org.
Chem., 71, 6942–6951 (2006).
22)ꢀ Sosaꢀ J.ꢀ R.,ꢀ Tudjarianꢀ A.ꢀ A.,ꢀ Minehanꢀ T.ꢀ G.,ꢀ Org. Lett., 10, 5091–
5094 (2008).
23) Maity P., Lepore S. D., J. Org. Chem., 74, 158–162 (2009).
24)ꢀ Schultzꢀ M.ꢀ K.,ꢀ Parameswarappaꢀ S.ꢀ G.,ꢀ Piggeꢀ F.ꢀ C.,ꢀ Org. Lett., 12,
2398–2401 (2010).
25)ꢀ HargroveꢀR.ꢀJ.,ꢀStangꢀP.ꢀJ.,ꢀJ. Org. Chem., 39, 581–582 (1974).
26)ꢀ Flemingꢀ I.,ꢀ Mwanikiꢀ J.ꢀ M.,ꢀ J. Chem. Soc., Perkin Trans. 1, 1998,
1237–1247 (1998).
27)ꢀ Ramharterꢀ J.,ꢀ Weinstablꢀ H.,ꢀ Mulzerꢀ J.,ꢀ J. Am. Chem. Soc., 132,
14338–14339 (2010).
tert-Butyl 5-Phenylpent-2-ynoate (6b) 1H-NMRꢀ(400ꢀMHz,ꢀ
CDCl3) δ:ꢀ 7.32–7.19ꢀ (5H,ꢀ m),ꢀ 2.89ꢀ (2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 2.58ꢀ
(2H,ꢀ t,ꢀ J=7.3ꢀHz),ꢀ 1.49ꢀ (9H,ꢀ s).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3)
δ: 152.8, 139.7, 128.5, 128.3, 126.5, 85.8, 83.0, 74.9, 33.9,
28.0 (3×C),ꢀ 20.8.ꢀ IRꢀ (CHCl3) cm−1: 2239, 1699, 1603, 1455,
1370,ꢀ 1285,ꢀ 1159,ꢀ 1074.ꢀ HR-EI-MSꢀ m/z: 230.1316 (Calcd for
C15H18O2: 230.1307).
tert-Butyl 7-(Benzyloxy)hept-2-ynoate (6c) 1H-NMRꢀ
(400ꢀMHz,ꢀCDCl3) δ:ꢀ7.37–7.27ꢀ(5H,ꢀm),ꢀ4.50ꢀ(2H,ꢀs),ꢀ3.49ꢀ(2H,ꢀ
t, J=5.9ꢀHz),ꢀ 2.33ꢀ (2H,ꢀ t,ꢀ J=6.8ꢀHz),ꢀ 1.77–1.65ꢀ (4H,ꢀ m),ꢀ 1.49ꢀ
(9H,ꢀ s).ꢀ 13C-NMRꢀ (100ꢀMHz,ꢀ CDCl3) δ: 152.9, 138.4, 128.5,
128.4, 127.6, 127.5, 86.6, 82.9, 74.6, 72.9, 69.5, 28.8, 28.0
(3×C),ꢀ 24.4,ꢀ 18.4.ꢀ IRꢀ (CHCl3) cm−1: 2235, 1699, 1495, 1477,
1454,ꢀ1370,ꢀ1283,ꢀ1159,ꢀ1079.ꢀHR-EI-MSꢀm/z: 232.1112 (Calcd
for C14H16O3 [M−C4H8]+: 232.1099).
28)ꢀ Hamajimaꢀ A.,ꢀ Isobeꢀ M.,ꢀ Angew. Chem. Int. Ed., 48, 2941–2945
(2009).
29)ꢀ MoritzꢀB.ꢀJ.,ꢀMackꢀD.ꢀJ.,ꢀTongꢀL.,ꢀThomsonꢀR.ꢀJ.,ꢀAngew. Chem. Int.
Ed., 53, 2988–2991 (2014).
30)ꢀ Cominsꢀ D.ꢀ L.,ꢀ Dehghaniꢀ A.,ꢀ Tetrahedron Lett., 33, 6299–6302
(1992).
31)ꢀ HargroveꢀR.ꢀJ.,ꢀStangꢀP.ꢀJ.,ꢀTetrahedron, 32, 37–41 (1976).
32)ꢀ Brummondꢀ K.ꢀ M.,ꢀ Dingessꢀ E.ꢀ A.,ꢀ Kentꢀ J.ꢀ L.,ꢀ J. Org. Chem., 61,
6096–6097 (1996).
Conflict of Interest Theꢀ authorsꢀ declareꢀ noꢀ conflictꢀ ofꢀ
interest.
33) Fleming I., Ramarao C., Chem. Commun., 1999, 1113–1114 (1999).
34) Fleming I., Ramarao C., Org. Biomol. Chem., 2, 1504–1510 (2004).
35)ꢀ Chassaingꢀ S.,ꢀ Specklinꢀ S.,ꢀ Weibelꢀ J.-M.,ꢀ Paleꢀ P.,ꢀ Tetrahedron, 68,
7245–7273 (2012).
36)ꢀ Specklinꢀ S.,ꢀ Bertusꢀ P.,ꢀ Weibelꢀ J.-M.,ꢀ Paleꢀ P.,ꢀ J. Org. Chem., 73,
7845–7848 (2008).
References
ꢀ 1)ꢀ ClarkꢀJ.ꢀH.,ꢀChem. Rev., 80, 429–452 (1980).
ꢀ 2)ꢀ Hanessianꢀ S.,ꢀ Devasthaleꢀ P.ꢀ V.,ꢀ Tetrahedron Lett., 37, 987–990
(1996).
ꢀ 3)ꢀ ItoꢀY.,ꢀHiguchiꢀN.,ꢀMurakamiꢀM.,ꢀHeterocycles, 52, 91–93 (2000).
ꢀ 4)ꢀ Kudybaꢀ I.,ꢀ Raczkoꢀ J.,ꢀ Jurczakꢀ J.,ꢀ Helv. Chim. Acta, 87, 1724–1736