Science of Synthesis

Hodgson, D. M.; Humphreys, P. G., Science of Synthesis, (2008) 36, 648.

The suprafacial [2,3]-sigmatropic rearrangement of allylic sulfoxides ‌159‌ in the presence of a thiophile such as trimethyl phosphite (Mislow–Evans rearrangement) generates E-allylic alcohols ‌160‌ typically in 70–80% yields.[‌348‌,‌349‌] The rearrangement is reversible, so the presence of a thiophile is essential to bias the equilibrium toward the desired allylic alcohol products.[‌350‌,‌351‌] Allylic sulfoxides can also be used to introduce further functionality by a deprotonation–alkylation sequence, prior to the addition of trimethyl phosphite that induces the rearrangement of the intermediate substituted sulfoxides ‌161‌ to afford the allylic alcohols ‌162‌ (‌Scheme 75‌).[‌352‌] The deprotonation/alkylation step is generally selective for alkylation at the α-position of the parent allylic sulfoxide, although the addition of ketones, aldehydes, or esters to the carbanions results in a substantial amount of electrophile trapping at the γ-position, even at −100°C.[‌348‌] Problems of competitive γ-alkylation with alkyl halide electrophiles can be overcome by the addition of a heterocycle at the sulfur atom such as 2-pyridyl or 2-imidazoyl, which allow predominantly α-alkylation due to the chelating effect of the heteroatom.[‌348‌] If a quaternary stereocenter is generated by deprotonation/alkylation then E/Z-alkene mixtures are typically generated, unless one substituent is substantially more sterically demanding than the other.

‌Meeeee 88‌ Meeeeeeeeeeee ee Meeeeeeeee ee Meeeeee Meeeeeee[‌888‌,‌888‌]

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‌Meeeee 88‌ Me Meeeeeeeeeee ee eee Meeeeeeeeeeee Meeeeeeeeee Meeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeee Meeeeeee ‌888‌; Meeeeee Meeeeeeee ee eee Meeeeeeeeeeee ee Meeeeeeeee:[‌888‌]

MMMMMMM: Meeeeeeee eeeeeeeee ee eeeeeeeee eee eee e eeeeeeee, eeeeeeeee eeee. Meeeeee eeeeeeee. Meeeee eeee eee eee eeeeeeee. Meeeeeeee eee eeeeeeeeee ee eee eeeeeeeeeee eeeee.

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References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) 8/8e8, 888.
• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) M 88-8, 888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.