Retro-ene type fragmentation of allylic dithiolcarbonates

Eto, Masashi; Nishimoto, Mitsuhiro; Kubota, Shôji; Matsuoka, T.; Harano, Kazunobu

doi:10.1016/0040-4039(96)00314-0

Cited by 12 publications

(5 citation statements)

References 11 publications

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“…The initial step of the sequential pericyclic reactions requires loss of resonance stabilization, and the energetically unfavorable S-(2-methylene-2,3-dihydrofuran-3-yl) S-methyl dithiocarbonate (2a) is considered to be formed as an intermediate. The succeeding COS extrusion from the intermediate (2a) proceeds through a six-membered cyclic TS5 which arises from the intermediate (2a) (retro alkylthio-ene reaction 8) ). The regain of the aromaticity of the furan ring plays an important role in the progress of the cascade reactions.…”

Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Furfuryl Sulfides from O-Furfuryl Dithiocarbonates: Density Functional Theory Study for Aromatic [3,3]-Sigmatropic Rearrangement

Eto

Yamaguchi

Yoshitake

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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Recently, we proposed a new reaction mechanism for the formation of allylic trithiocarbonate from sodium O-(2-alkenyl) dithiocarbonate, 1) in which a suspension of sodium hydride in benzene, containing 2-alkenol and an excess of carbon disulfide is heated to obtain the corresponding di(2-alkenyl)trithiocarbonates in good yields.2,3) The trithiocarbonates are convenient precursors of the thermodynamically stable allylic thiols (Chart 1).Based on data obtained from density functional theory (DFT) calculations at the B3LYP/6-31G(d) level, we demonstrated that sodium O-(3-phenylallyl) dithiocarbonate undergoes [3,3]-sigmatropic rearrangement to form sodium S-(1-phenylallyl) dithiocarbonate, which then allylically isomerizes to the more thermodynamically stable sodium S-(3-phenylallyl) dithiocarbonate.Furfuryl and benzyl alcohols were subjected to xanthation in dimethyl sulfoxide (DMSO) containing excess CS 2 in the presence of NaOH followed by alkylation to give the mixtures of trithiocarbonates. 3)On the other hand, it was observed that heating of O-furfuryl S-alkyl dithiocarbonates (xanthates) (1) afforded furfuryl alkyl sulfides (3) together with S-furfuryl S-alkyl dithiocarbonates (2). It was initially assumed that the sulfide (3) had formed via an intramolecular SNi-type fragmentation reaction mechanisms (Chart 2). 4)These considerations prompted us to reinvestigate the key step of the conversion of the furfuryloxy (ArCH 2 O-) moiety to the furfurylthio (ArCH 2 S-) moiety in the formation of the trithiocarbonate from sodium O-furfuryl dithiocarbonates as well as in the formation of S-furfuryl S-alkyl dithiocarbonates (2) and furfuryl alkyl sulfides (3) from O-furfuryl Salkyl xanthates (1) with the assumption that aromatic [3,3]-sigmatropic rearrangement was operative. This paper presents a detailed discussion of the reaction mechanisms in the formation of O-furfuryl dithiocarbonates on the basis of the DFT calculations 5) at the B3LYP/6-31G(d) and B3LYP/6-31Gϩ(d) levels. Results and DiscussionRearrangement of O-Furfuryl Dithiocarbonate Anion (1-Anion) On the basis of the reaction behavior of the Oallyl dithiocarbonate anion, 1) two possible reaction pathways were proposed for the formation of the S-furfuryl dithiocar- ; 4-22-1 Ikeda, Kumamoto 869-1404, Japan: and b Liberal Arts Education Center, Aso Campus, Tokai University; 5435 Kawayo, Minami-Aso, Kumamoto 869-1404, Japan. Received October 27, 2010 accepted February 28, 2011; published online March 7, 2011 Density functional theory (DFT) calculations at the B3LYP/6-31G(d) and B3LYP/6-31G؉(d) levels demonstrated that O-furfuryl S-alkyl dithiocarbonate (1) undergoes aromatic [3,3]-sigmatropic rearrangement to the energetically unfavorable S-(2-methylene-2,3-dihydrofuran-3-yl) S-alkyl dithiocarbonate (2), which then rearranges to furfuryl alkyl sulfide (3) with COS extrusion to regain the aromaticity lost in the first step. Formation Mechanism of Furfuryl Sulfides from O-Furfuryl

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Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Furfuryl Sulfides from O-Furfuryl Dithiocarbonates: Density Functional Theory Study for Aromatic [3,3]-Sigmatropic Rearrangement

Eto

Yamaguchi

Yoshitake

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Original HRMS spectra for compounds 9, 24, S2, [15][16][17][18]21,23,24,25,28,30,32,34a,34b,and 38 (PDF) FAIR data, including the primary NMR FID files, for compounds 6, 9, 12−21, 23−25, 28, 30, 32−34, 37− 39, and…”

Section: * Sı Supporting Informationmentioning

confidence: 99%

“…Heating 28 in benzene at 90 °C afforded the dithiolcarbonate 30 predominantly in 72% yield via TS-29 (path A), 14 while the unexpected retro-Ene-type fragmentation occurred simultaneously to produce 2-alkenyl methyl sulfide 32 in 24% yield via TS-31 (path B). 15 Exposing 30 to ethanolamine under air achieved the disulfide 33, 16 which was treated by P(NEt 2 ) 3 to smoothly furnish 32, with the stereochemistry at C 18 maintained. 17 The relative configurations of 30, 32, and 33 were established by extensive spectroscopic analysis including NOE analysis (see the Supporting Information for details).…”

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confidence: 99%

“…Alternatively, we prepared the xanthate 28 from 25 , as a precursor of [3,3]-sigmatropic rearrangement. Heating 28 in benzene at 90 °C afforded the dithiolcarbonate 30 predominantly in 72% yield via TS- 29 (path A), while the unexpected retro-Ene-type fragmentation occurred simultaneously to produce 2-alkenyl methyl sulfide 32 in 24% yield via TS- 31 (path B) . Exposing 30 to ethanolamine under air achieved the disulfide 33 , which was treated by P(NEt 2 ) 3 to smoothly furnish 32 , with the stereochemistry at C 18 maintained .…”

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Synthetic Study Aiming at the Tricyclic Core of 12-epi-JBIR-23/24

Man

Zhou

et al. 2021

Org. Lett.

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The synthetic study toward highly enantio-and diastereoselective synthesis of the tricyclic framework of 12-epi-JBIR-23/24, a natural product analogue showing inhibitory activity against four malignant pleural mesothelioma cell lines, is presented herein. In this synthesis, a rhodium-catalyzed asymmetric three-component Michael/aldol reaction introduces three consecutive tertiary carbon centers, while the unique epoxyquinol core motif is successfully forged via [3,3]-sigmatropic rearrangement of an allylic xanthate, vinylogous Pummerer rearrangement, and a selective mesylation/epoxidation cascade of a triol.

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“…In the latter procedure, the transformation from the dithiocarbonate anion to the trithiocarbonate anion is considered to be caused by sequential retro-ene [2sϩ2sϩ2p] and ene [2pϩ2pϩ2s] reactions (Chart 4), 17) in which the intermedi- ary compound (RCHϭCHCH 2 SNa) can attack the thiocarbonyl carbon atom of 3-Na to give di(2-alkenyl)trithiocarbonate (3) and Na 2 S.…”

Section: New Formation Mechanism Of Allylic Trithiocarbonates From Somentioning

confidence: 99%

New Formation Mechanism of Allylic Trithiocarbonates from Sodium O-(2-Alkenyl) Dithiocarbonates via Sequential Pericyclic Reactions: Density Functional Theory Study

Eto

Yamaguchi

Yoshitake

et al. 2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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Density functional theory (DFT) calculations at the B3LYP/6-31G(d) level demonstrated that sodium O-(3-phenylallyl) dithiocarbonate undergoes [3,3]-sigmatropic rearrangement to sodium S-(1-phenylallyl) dithiocarbonate, which then isomerizes to the more thermodynamically stable sodium S-(3-phenylallyl) dithiocarbonate. The calculations also showed that sodium 2-alkenyl trithiocarbonates and their esters are more labile towards the allylic rearrangement.

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Retro-ene type fragmentation of allylic dithiolcarbonates

Cited by 12 publications

References 11 publications

Formation Mechanism of Furfuryl Sulfides from O-Furfuryl Dithiocarbonates: Density Functional Theory Study for Aromatic [3,3]-Sigmatropic Rearrangement

Formation Mechanism of Furfuryl Sulfides from O-Furfuryl Dithiocarbonates: Density Functional Theory Study for Aromatic [3,3]-Sigmatropic Rearrangement

Synthetic Study Aiming at the Tricyclic Core of 12-epi-JBIR-23/24

New Formation Mechanism of Allylic Trithiocarbonates from Sodium O-(2-Alkenyl) Dithiocarbonates via Sequential Pericyclic Reactions: Density Functional Theory Study

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