Magnesium alkylidene carbenoids generation

The magnesium alkylidene carbenoid generated occurs in equilibrium between... 

A. Generation and Nucleophilic Property of Magnesium Alkylidene Carbenoids, the Fritsch-Buttenberg-Wiechell Rearrangement... 

Stereochemistry of this reaction is also quite interesting. Thus, both geometrical isomers of 1-chlorovinyl p-tolyl sulfoxides (165-167) were synthesized from 2-cyclohexenone, methyl vinyl ketone and 2-heptanone respectively, and the corresponding magnesium alkylidene carbenoids were generated and treated with A-lithio aniline or A-lithio 1-aminonaphthalene. The results are summarized in Table 9. 

Treatment of magnesium alkylidene carbenoids, which were generated from 1-chlorovinyl /)-tolyl sulfoxide 161 with isopropylmagnesium chloride at —78°C in toluene, with AT-lithioindazole 162 (or pyrazole) gave N-alkenylated indazole 163 in moderate yield (Scheme 5) <2005TL4855>. Reaction of lithiopyrazole gave the N-alkenylated pyrazole but in a lower yield. 

---