Endocyclic vs. exocyclic attack in nucleophilic displacement reactions on five- and six-membered cyclic onium salts

Eliel, Ernest L.; Hutchins, Robert O.; Mebane, Robert.; Willer, Rodney L.

doi:10.1021/jo00868a027

Cited by 53 publications

(18 citation statements)

References 5 publications

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“…In line with the first of these predictions, Eliel et al have shown that azide ion attack on the S-methylthianium iodide (lob) gives thiane and methyl azide (6). We found that thiocyanate ion behaved similarly: reaction of 10c with potassium thiocyanate gives thiane and only ca.…”

Section: Ch3supporting

confidence: 87%

“…We reasoned that the first of these requirements would be met as a consequence of the release of torsional strain, as well as entropy, and statistical factors. Examination of the literature reveals excellent precedent for this in the report of Eliel et al (6) that the reaction of azide and thiolate anions with 3a gave predominantly the products of ring opening, 4 and 5, respectively, but we decided to submit the matter to direct test.…”

Section: Introductionmentioning

confidence: 99%

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A simple, biogenetically modeled synthesis of 4-(methylthio)butyl thiocyanate: the reaction of thiocyanate anion with S-methyl-(1,n)-epithionium ions

Benn¹,

Singh²

1986

Can. J. Chem.

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. J. Chem. 64, 940 (1986).The reaction of S-methylthiolanium fluorosulphate with thiocyanate ion gives predominantly 4-(methy1thio)butyl thiocyanate, a result which is in accord with a hypothesis for the biogenesis of this compound, and which has implications for the natural occurrence of analogous thiocyanates.M. H. BENN et VINOD K. SINGH. Can. J. Chem. 64, 940 (1986).La rkaction du fluorosulfate du S-mt5thylthiolanium avec l'ion thiocyanate conduit principalement au thiocyanate de (mt5thyl-thio)-4 butyle; ce rt5sultat est en accord avec une hypothbse relative h la biogknbse de ce compost5 et il a des implications relativement h l'existence h 1'Ctat nature1 de thiocyanates analogues.[Traduit par la revue] Introduction Glucosinolates are naturally occurring anions, characterized by the general structure 1. They are commonly, but not exclusively, encountered within plants of families that constitute the Capparales and their decomposition is a matter of considerable current interest, because the products are known to be important factors in determining the palatability and toxicity of these plants to man and other animals (see ref. 1, and references therein).Of the nearly 100 glucosinolates that have been isolated, or inferred to exist, all can be catabolized to isothiocyanates or nitriles. These products are known to arise from the-aglucones that are released from 1 by myrosinase (thioglucoside glucohydrolase EC 3:2:3:1) (Scheme 1) (1). In contrast with this generality, only three, the allyl (2), benzyl (2, 3), and 4-(methylthio)butyl(4) compounds are known to be capable of yielding the corresponding thiocyanates, and they do so under conditions that indicate that these conversions involve other, plant-specific, enzymes.To account for this striking restriction it has been postulated (5) that the thiocyanates are formed from aglucones by a fragmentation process in which departure of sulphate, instead of being concerted with the [1,2]-shift of the substituent R that yields the isothiocyanates, results in fragmentation to thiocyanate anion and a cation corresponding to R. Recombination of this ion pair would then be expected to preferentially form the thiocyanate as a consequence of the high nucleophilicity of the S-terminus of the ambident thiocyanate anion. Also plausible is the possibility that the fragmentation process is a consequence of a Z-, E isomerization that destroys the geometry required for the concerted isothiocyanate-forming reaction (Scheme 2) (5). (The aglucone intermediates are shown in Schemes 1 and 2 in their free, protonated, forms. It may well be that they are bound, through bivalent sulphur, to a metal ion: this would inhibit tautomerism and interconversion of E and Z isomeric forms.)Fragmentation should be favoured for substrates that yield relatively stable cations. The allyl and benzyl systems are textbook examples of such ions, and we visualized 4-(methylthio)butyl glucosinolate (2) (n = 4) as yielding the even more stable S-methylthiolanium cation. In this latter case there is then a requ...

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Section: Ch3supporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

A simple, biogenetically modeled synthesis of 4-(methylthio)butyl thiocyanate: the reaction of thiocyanate anion with S-methyl-(1,n)-epithionium ions

Benn¹,

Singh²

1986

Can. J. Chem.

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“…Selective cleavage of organic polysulfide (S-S) bonds was performed in order to characterize sulfur in OM based on the method of Eliel et al (1976) and Kohnen et al (1991). Excess methyl lithium (MeLi) was added to 50-100 mg of OM in diethyl ether.…”

Section: Chemical Degradation Of the Residual Om By Meli/meimentioning

confidence: 99%

Experiments on δ34S mixing between organic and inorganic sulfur species during thermal maturation

Amrani

Said-Ahamed

Lewan

et al. 2006

Geochimica et Cosmochimica Acta

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“…Chemical degradation of the residual OM by CH 3 Li/ CH 3 I or CD 3 Li/CD 3 I Selective cleavage of organic polysulfide (S-S) bonds was performed in order to characterize sulfurized OM (Eliel et al, 1976;Kohnen et al, 1991). To 50-100 mg of OM in dry diethyl ether, an excess of methyl lithium (MeLi) was introduced and the mixture stirred at ambient temperature.…”

Section: Reaction Between Polysulfides and Aldehydesmentioning

confidence: 99%

“…MeLi/MeI treatment of the PCLM cleaves S-S bonds and adds a methyl group to each sulfur moiety, enabling analysis of methylated monomers by GC-MS (Eliel et al, 1976;Kohnen et al, 1991). However, MeLi/MeI treatment methylates carbonyl and imine groups (Grignard type mechanism) as well as thiol and amine groups.…”

Section: Chemical Degradation Followed By Gc-ms Studiesmentioning

confidence: 99%

Formation of sulfur and nitrogen cross-linked macromolecules under aqueous conditions

Amrani

Turner

et al. 2007

Geochimica et Cosmochimica Acta

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Endocyclic vs. exocyclic attack in nucleophilic displacement reactions on five- and six-membered cyclic onium salts

Cited by 53 publications

References 5 publications

A simple, biogenetically modeled synthesis of 4-(methylthio)butyl thiocyanate: the reaction of thiocyanate anion with S-methyl-(1,n)-epithionium ions

A simple, biogenetically modeled synthesis of 4-(methylthio)butyl thiocyanate: the reaction of thiocyanate anion with S-methyl-(1,n)-epithionium ions

Experiments on δ34S mixing between organic and inorganic sulfur species during thermal maturation

Formation of sulfur and nitrogen cross-linked macromolecules under aqueous conditions

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