Synthesis of γ,δ-Unsaturated Dithioacids, 1-Alkenyl Alkanedithioates, and γ-Dithiolactones from 2-Alkenyl Alkanedithioates

Schoufs, M.; Meijer, J.; Vermeer, P.; Brandsma, L.

doi:10.1055/s-1978-24772

Cited by 16 publications

(11 citation statements)

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“…In our preceding study, 5 we reviewed recent calculations of the parent Cope and Claisen rearrangements; in the light of the work of Borden 6 and Davidson, 7 it seems well established that the former [3,3] sigmatropic shift is concerted and does not involve the formation of a diradical intermediate. On the basis of this result, we assumed that the reaction studied here occurs along a concerted reaction pathway and thus we decided to employ single reference techniques.…”

Section: Methodsmentioning

confidence: 99%

“…In many cases, single-point energies were computed up to Fig. 1 Optimized geometries of the transition structures on the [3,3] sigmatropic rearrangements calculated at the HF and B3LYP (italicised) levels MP4SDTQ and QCISD(T) levels using B3LYP optimized geometries. Zero-point vibrational energies (ZPE) were scaled by 0.9135.…”

Section: Methodsmentioning

confidence: 99%

“…The transition structures of [3,3] sigmatropic rearrangements depicted in Scheme 1 are shown in Fig. 1.…”

Section: Structures and Energiesmentioning

confidence: 99%

“…In the thioketone series (Scheme 1, X = CH, R = alkyl, RЈ = RЉ = H), these sigmatropic processes have been shown to be reversible. 2 This synthetic limitation was not observed for dithioesters (X = CH 2 , R = SR, RЈ = RЉ = H) 3 and for O-substituted thioesters (X = CH 2 , R = OR, RЈ = RЉ = H). 4 We previously reported a theoretical study of the thio-Claisen rearrangement of the unsubstituted allyl vinyl sulfide and of one of its aza analogues, vinylthioethanimine (Scheme 1, XRЉ = NH Z and E, R = RЈ = H).…”

Section: Introductionmentioning

confidence: 99%

“…Thio-Claisen rearrangements are important [3,3] sigmatropic shifts widely used in synthetic organic chemistry. 1 The simplest allyl vinyl sulfide (Scheme 1, X = CH 2 , R = RЈ = RЉ = H) easily leads to an unstable thioaldehyde, pentenethial.…”

Section: Introductionmentioning

confidence: 99%

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Substituent effect on the allyl vinyl sulfide rearrangement (thio-Claisen rearrangement) and the vinylthioethanimine rearrangement. A theoretical study

Arnaud¹,

Vallée²

1997

J. Chem. Soc., Perkin Trans. 2

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The transition structures for the [3,3] sigmatropic rearrangements of a variety of substituted allyl vinyl sulfides (X᎐ ᎐ CH) and vinylthioethanimines (X᎐ ᎐ N) H 2 C᎐ ᎐ CR᎐S᎐CH 2 ᎐CRЈ᎐ ᎐ XRЉ (R = NH 2 ; RЈ = BH 2 , CN; RЉ = CF 3 ) have been located using ab initio and DFT (B3LYP) calculations and the 6-31G* basis set. Relative energies have been estimated using post-HF calculations up to the QCISD(T)/6-31G*//B3LYP/ 6-31G* level. Solvent effects on these processes have been simulated by means of SCRF computations associated with a continuum model. The results show that combined donor-acceptor disubstitutions (R = NH 2 , RЈ = BH 2 or CN) improve considerably the reactivity of the allyl vinyl sulfide (vinylthioethanimine). Thus, 2-amino-5-cyano disubstitution lowers the enthalpy of activation by 6.6 kcal mol Ϫ1 (9.3 kcal mol Ϫ1 ) (1 cal = 4.184 J) and increases the exothermicity of the rearrangement by 13.0 kcal mol Ϫ1 (19.1 kcal mol Ϫ1 ). In addition, as the corresponding saddle points are highly polar in nature, an additional transition state stabilization, even in moderately polar solvents, is predicted by the SCRF calculations.

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