Science of Synthesis

Kostikov, R. R.; Khlebnikov, A. F.; Sokolov, V. V., Science of Synthesis, (2010) 47, 844.

Earlier information about the reductive desulfurization of thiiranes leading to alkenes can be found in Houben–Weyl, Vol. 5/1b, p 204, and in other sources.[‌202‌,‌290‌] This approach to alkenes has relatively rarely been used in organic synthesis because thiiranes are much less easily available starting materials than other precursors. As the most versatile methods for the preparation of thiiranes start with the treatment of the corresponding oxiranes with alkali metal thiocyanates, thioamides, or similar agents, desulfurization of thiiranes can be considered as a multistep procedure for deoxygenation of oxiranes (see Section ‌47.1.4.8.1‌). Important precursors of sterically encumbered thiiranes (and hence alkenes) are 2,5-dihydro-1,3,4-thiadiazoles, obtained from thiocarbonyl and diazo compounds[‌291‌,‌292‌] or from carbonyl compounds, hydrazine, and hydrogen sulfide.[‌293‌] In contrast to oxiranes, for which a carbophilic attack of nucleophiles is typical, thiiranes exhibit a great tendency to thiophilic attack, leading to sulfur extrusion and thus alkene formation with retention of configuration. The classical reagents for such types of desulfurization are phosphines (e.g., to give ‌129‌ from ‌128‌) and phosphites (see also Houben–Weyl, Vol. 5/1b, p 204);[‌202‌,‌290‌–‌296‌] the reduction with triphenylphosphine can be catalyzed by methyltrioxorhenium(VII)–hydrogen sulfide (‌Table 41‌).[‌297‌] Alternative reagents for stereospecific desulfurization are halotrimethylsilanes (halo = Br, I),[‌298‌,‌299‌] dicarbonylchlororhodium(I) dimer,[‌300‌] and a zirconium–iridium complex (Cp)2Zr(μ-N-t-Bu)Ir(Cp*).[‌301‌] Butyllithium also reacts with a certain degree of stereoselectivity (e.g., providing ‌131‌ from ‌130‌),[‌302‌,‌303‌] whereas in the cases of tributyltin hydride,[‌304‌,‌305‌] nickel–ethanol, lithium–ethylamine, zinc–acetic acid, and diphosphorus tetraiodide–dimethylformamide[‌304‌] a lack of chemo- and/or stereoselectivity is observed, and the stereochemistry of desulfurizations with sodium–toluene has not been determined.[‌306‌]

‌Meeee 88‌ Meeeeeeeeeeeeee ee Meeeeeeee[‌888‌,‌888‌,‌888‌,‌888‌,‌888‌,‌888‌,‌888‌,‌888‌]

Meeeeeee Meeeeeee	Meeeeeeeee	Meeeeee	Meeee (%)	Mee
	Me8M, eeeeee, eeee, 8 e		88	[‌888‌]
	Me8M, MMM, eeee, eeeeeeeee		88	[‌888‌]
	Me8M, 88°M, 8 e		88	[‌888‌]
	Me8M, 88°M, 8 e		88	[‌888‌]
	MeMeM8 (8 eee%), M8M, MM8MM, ee, 8 eee, eeee Me8M, 8 eee		888	[‌888‌]
	MeMeM8 (8 eee%), M8M, MM8MM, ee, 8 eee, eeee Me8M, 8 e		888	[‌888‌]
	MMMMe, MeM, ee, 8 e		88e	[‌888‌]
	Me8Me8(MM)8 (8 eee%), MM (88 × 888 Meee), eeeeeee, ee, 88 e		88	[‌888‌]
	MeMe, MMM/eeeeee, −88°M, 8 e		88	[‌888‌]
	Me8MeM, MMMM, eeeeeee, eeee, 88 eee		88	[‌888‌]

e MMM eeeee.

Mee eeeeeee eeeeeeeeeee eee eeeeeeeeeeee eee eeeeeeee eee eeee eeeeeeeee eeeeeeee ee eeeeeeeee eeeeeeeeeeeee; eeeeeeeee, eee eeeeeeeee eee ee eeee eeeeeeeeeeeee ee eeee eeeeeeeeeeeee eee eeee ee eeee eee eee eeeeeeeeeee ee eeeeeee.[‌888‌,‌888‌–‌888‌]

Meeeeeee 8,8-eeeeeeee eee eeeee eee eee eeeee eeeeee eeeee eeeeeee eeeeeeeeee, eee eeee eeeeeee eeeeeee eeeeeee eeeeeeeeeeeee eeee eeeeeeeeeeeeee eeeeeeeeeee eeeeeeeee ee eeeeee eeeeeee ee eeee eeeeeee. Meeeee eeeeeeeee ee eeeeeeeee ee eee e eeeeee eeeeee; eeeeeeeee, e eeeeee ee eeeeeeeee eeeeeeeee eee eeeeee eeeeeeeeeee eeeeeeeee eee eeeeeeeee eee eeeee ee eeeeeeee 8,8-eeeeeeee eee eeee eeeeeeeee. Mee eeee eeeeeeeee ee eeee ee eee Meeeeee–Mäeeeeee eeeeeeee, eeeee ee eeeeeeeeee eeeeeeeeee (Meeeeee ‌88.8.8.8.8‌). M eee-eeee eeeeeeeee eee eee eeeeeeeeeee ee eeeeeeeeeee eeeeeee ‌888‌ eeeeeeee ee eeeeeeeee ee eeeeeeeeeeeeee eeeeeeeee ‌888‌ eeee eeeeeeee eeeeee, eeeeeeeee eee eeeeeeeeeee eeeeeeee 8,8-eeeeeeee ‌888‌, eeeeeeee ee eeeee eeeeeee eeeeeeeeeeeee.[‌888‌] Mee eeeeeee eeeeeeee ee eeee eeeeee ee eee eee eeeeeeeeeeeeeeeee. M eeeeeeee eeeeeeeeeee ee eee Meeeeeeeee–Meeeeeeeee eeeeeeee, eeeee eeeeeeee eee eeeeeeeee ee eeeeeeeeeee eeeeeeee 8,8-eeeeeeee ‌888‌ eeee eeeee eeeeeeeee ‌888‌ eee eeeeee eeeeeee, eee eee eeee eeee eee eee eeeeeeeeeee ee 8,8,8,8-eeeeeeeeeeeeee-8-eee (‌888‌; ‌Meeeee 88‌)[‌888‌] eeeeeeeee,[‌888‌,‌888‌], eeeeeee,[‌888‌] eee eeeee eeeeeee.[‌888‌] Meeeeeeeeeeee, e eeeeee ee eeee eeeeeeeee eeeeee eee eeeeeeee 8,8-eeeeeee eeeeeeeee ee eeee eeeeeeeee.

‌Meeeee 88‌ Meeeeeeee eee Meeeeeeeeeeee ee Meeeeeee 8,8-Meeeeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

(M)-Meee-88-eee (‌888‌); Meeeeee Meeeeeeee:[‌888‌]

MMMMMMM: Meee eeeeeeeeeee eeeeee ee eeeeeeeee ee e eeee-eeeeeeeeee eeee.

MMMMMMM: Meeeeeeeee, eeeeeeeee, ee eeee eeeeeeeeee ee eeeeeeeeeee eee ee eeeee.

M eeeeeee ee eee-8,8-eeeeeeeeeeeeeee (‌888‌; 8.8 e, 8.8 eeee), Me8M (8.8 e, 8.8 eeee), eee MMM (888 eM) eee eeeeee eeeee eeeeee eeeee e M8 eeeeeeeeee eeeeeeeee. Mee eeeeeee eee eeeeee ee ee, eee MeM (8 eM) eee eeeee. Meeeeeeeeee ee eee eeeeeee eeee e eeeee, eeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee) ee eeeeee e eeeeeeeee eeeeee; eeeee: 8.88 e (88%); MM-MM (eeee) ν̃eee: 8888, 8888, 8888, 8888, 8888, 8888, 888, 888 ee-8; 8M MMM (MMMe8, δ): 8.88 (e, M = 8 Me, 8M), 8.88 (e, 88M), 8.88 (e, 8M), 8.88 (e, M = 8.8 Me, 8M).

(M)-8,8-Meeeeeee-8-eeeeeeeee-8-eee (‌888‌); Meeeeee Meeeeeeee:[‌888‌]

Me e eeee ee eeeee-8-eeee-eeeee-8-(8-eeeeeeeeeee)eeeeeeee (‌888‌; 88.8 ee, 8.888 eeee) ee MMM (8 eM), eeeeee ee −88°M eee eeee eeeee e M8 eeeeeeeeee, eee eeeee e 8.88 M eeee ee MeMe ee eeeeee (8.88 eM, 8.888 eeee) eeee e eeeeeee, eee eee eeeeeee eee eeeeeee eee 8 e. Me eee eeeeee ee ee eeeeeeeee, eee eee eeeeeeee eee eeeeeeee eeee M8M. Mee eeeeeee eeeee eee eeeeeeeee eeee eeeeeee, eee eee eeeeeeee eeeeeee eeeeee eeee eeeee (MeMM8) eee eeeeeeeeeeee. Mee eeeeeee eee eeeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, Me8M/eeeeee 8:88) ee eeee eee eeeeeee ee e eeeeee; eeeee: 88.8 ee (88%); MM (eeee) ν̃eee: 8888, 8888 ee-8; 8M MMM (MMMe8, δ): 8.88 (e, 8M), 8.88 (e, 8M), 8.88 (ee, M = 8.8, 8.8 Me, 8M), 8.88 (ee, M = 88.8, 8.8 Me, 8M), 8.88 (e, M = 88.8 Me, 8M), 8.88–8.88 (e, 8M).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 8e8, 888.
• 8.Meeeee-Meee, (8888) M 8e, 888.
• 8.Meeeee-Meee, (8888) M 8e, 888.