Organic sulfur chemistry. X. Selective desulfurization of disulfides. Scope and mechanism

Abstract

water was added and the organic layer was dried (MgS04). Evaporation of the ether and distillation of the residue at 15 Torr gave 1.5 g of material, bp 70-74°, that was further purified by preparative glpc on a QX-1 column at 110°; nmr (CC14) 6 0.93 (s, 6), 1.05(s, 6), 5 9(d, 1,7 = 10Hz), 7.4(d, 1,7 = 10Hz).

On the Determination of the Stereochemistry of Semisynthetic Natural Product Analogues using Chiroptical Spectroscopy: Desulfurization of Epidithiodioxopiperazine Fungal Metabolites

“…Such S N 2-type displacement of the phosphonium intermediate has precedence in desulfurization chemistry, [24] particularly using aminophosphines. [25] Consistent with this mechanism, studies by Barbier and co-workers determined that conversion of sirodesmin PL to its monosulfide derivative 8 (see Scheme 1) proceeded with retention of configura- www.chemeurj.org tion.…”

“…[14] Following nucleophilic cleavage of the disulfide bond by triphenylphosphine (to give 10), [24,25] they proposed elimination of triphenylphosphine sulfide to give species 11, which could undergo ringclosing to give monosulfide 12 a with retention of stereochemistry. Although this mechanism appears satisfactory, it cannot explain the results of Ottenheijm and co-workers, who unambiguously showed that ETP analogue 5 (see Scheme 1) was desulfurized to give the (S,S)-monosulfide 6, with inversion at both centers.…”

Dechalcogenative Allylic Selenosulfide and Disulfide Rearrangements: Complementary Methods for the Formation of Allylic Sulfides in the Absence of Electrophiles. Scope, Limitations, and Application to the Functionalization of Unprotected Peptides in Aqueous Media.

“…Under the same conditions the phenyl geranyl disulfide 20, however, gave the unrearranged phenyl geranyl sulfide 21 (Table 1, entry 2), thereby drawing attention to the relatively fine dividing line between the desired dechalcogenative allylic rearrangement and the better known nucleophilic removal of a sulfur atom from a disulfide. 68 As is evident from the comparison of entries 1 and 2 in Table 1, the replacement of an alkylthiyl moiety by an arylthiyl group is sufficient to tip the balance in favor of nucleophilic attack by the phosphine on the native disulfide. Entry 3 of Table 1 illustrates how the replacement of PPh 3 by the more nucleophilic hexaethylphosphoramine enabled the reaction temperature to be reduced to the ambient but, unfortunately, with continued formation of the simple desulfurization product.…”

Hexamethylphosphorous Triamide

“…Alkyl, aralkyl, and alicyclic disulfides undergo facile desulfurization to the corresponding sulfides on treatment with (Me 2 N) 3 P or (Et 2 N) 3 P (eq 13). 10 For example, reaction of methyl phenyl disulfide with (Et 2 N) 3 P in benzene at rt for ∼1 min furnishes methyl phenyl sulfide in 86% yield. The desulfurization process is stereospecific, in that inversion of configuration occurs at one of the carbon atoms α to the disulfide group.…”