Heteroatomic coupling nitrogen nucleophiles

In the penem series, 2-(heteroatom-substituted)-methyl derivatives have been similarly prepared via the 2-(hydro-xymethyl) key intermediate 71. Some examples of this C-2 functionalization are illustrated in Scheme 39 <1990H(30)799, 1995JME4244>. The reactions involved are O-acylation 72, O-arylation 73 by Mitsunobu coupling, and substitution by nitrogen nucleophiles 74 after OH activation by mesylation. 

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