Science of Synthesis

Griesbeck, A. G.; Soldevilla, A., Science of Synthesis, (2008) 43, 383.

The introduction of the Bestmann–Ohira reagent,[‌156‌–‌158‌] dimethyl (1-diazo-2-oxopropyl)phosphonate (‌93‌) (see also Section ‌43.8.2.1.4‌), in a modification of the Seyferth–Gilbert process, allows the synthesis of terminal alkynes ‌95‌ directly from aromatic aldehydes at room temperature under mild conditions using mild bases (‌Scheme 48‌).[‌159‌] Synthesis of the reagent is most convenient on a multigram scale by diazo group transfer from 4-acetamidobenzenesulfonyl azide (preferred to tosyl azide) to dimethyl 2-oxopropylphosphonate (‌92‌) (‌Scheme 48‌).[‌160‌] Aldehydes can be generated from Weinreb amides or from esters by reduction with diisobutylaluminum hydride and directly used for further reaction with the Bestmann–Ohira reagent.[‌161‌] Alternatively, benzylic alcohols ‌94‌ are converted by oxidation with activated manganese dioxide into the corresponding aldehydes and subsequently treated with the alkynylation reagent.[‌162‌]

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‌Meeeee 88‌ Meeeeeee–Meeee Meeeeeeeeeee ee [8,8]Meeeeeeeeeeeee-8,88-eeeeeeeeee[‌888‌]

Meee eee eeeeeeeeee eeee ee “eeeee” eeeeeeeee ee eeeeeee eeeeeeeee (eeeeeeeee eeee eeeee eeeeeee eee eeee eee eeeeeee ee eeeeee, eee eeeeeee eee eeeeeeeee ee eeeeeeeeee), eee ee eeee eeeeeeeeee ee eeeeeee ee eee eeeeeeee ee eeeeeee eeeeee eee eeeeee eeeeeeeee. Mee Meeeeeee–Meeee eeeeeee ee eeee eeeeee eee eeeee eeeeeeee eeeeeeeeee, eee 8,8,8-eeeeeeee ‌88‌ eee ee eeee ee eeeeeeeee eeeeee ee ee eeee eeeeeeeeee ee eeeeeee eee eeeeeeeeee eeeeee-eeeeeeeee eeeee–eeeeee 8,8-eeeeeee eeeeeeeeeeeee (MeMMM) (‌Meeeee 88‌).[‌888‌]

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Meeeeeeeeeee Meeeeeeee

Meeeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌888‌]

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References

Meeeeee Meeeeeeeeee

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