Seyferth-Gilbert reagent

This Seyferth-Gilbert reagent is conveniently prepared through trifluoroacetylation and diazo transfer with concomitant detrifluoroacetylation. ... 

It is proposed that this reaction occurs via a mechanism similar to the Wittig Reaction In detail, deprotonation of the Seyferth-Gilbert reagent by potassium -butoxide generates a carbanion, which adds to the carbonyl group to yield an oxaphosphatane then subsequent elimination of dimethylphosphate leads to the formation of a vinyl diazo intermediate from which the vinyl carbene forms by evolution of nitrogen gas final 1,2-migration of the substituent on vinyl carbene yields the alkyne. An illustrative mechanism is displayed here. 

We have already seen the bishydroxylation using 0s04 and NMO this time lead tetraacetate is used to cleave the diol and yield the aldehyde. The phosphorane (Me0)2P(0)CHN2 is named the Gilbert-Seyferth reagent. 8 It basically behaves like the phosphoranes in the Horner-Wadsworth-Emmons reaction described above, except that the olefin subsequently loses nitrogen, creating the desired triple bond (also see Chapter 10). 

---