Regioselective O-Alkylations of Indazolinone Using (Cyanomethylene)triphenylphosphorane

Abstract

Regioselective O-alkylation of indazolinones using (cyanomethylene)-triphenthylphosphorane (CMPP) as a Mitsunobu-type reagent is described with a variety of aliphatic alcohols. This method was also successfully applied to the N-alkylation of O-protected indazolinone. Selective N1 and N2 alkylations on indazolinone have previously been described; our methodology is therefore orthogonal to the previous precedent.

Key words

alkylations - heterocycles - ylides - Mitsunobu - trialkyl­phosphoranes

References and Notes

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8

These reactions were not heated for safety reasons and this is probably why unlike Selwood (ref. 5) we saw no reaction.

16

ACD PK _a predictor suggests (Figure  [³] )

Figure 3

17

NMR and LC-MS data confirm that 6a and 7a are diasteromers. Based on mechanism inversion in assumed, but this has not been confirmed experimentally.