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8.1.21.4.3.5 Variation 5: Electrophilic Substitution of Aldehyde Homoenolate Synthons

DOI: 10.1055/sos-SD-008-00412

Gawley, R. E.; O'Connor, S.; Klein, R.Science of Synthesis, (20068734.

The η3-α-lithioamine species shown in Scheme 61 (derived from 129; see Section 8.1.21.4.3.4) undergoes reaction with several electrophiles at the γ-position relative to nitrogen. With benzyl bromide, electrophilic substitution occurs with inversion (e.g., to give 133); however, with enones, ketones, and nitroalkenes, it occurs with retention, giving compounds such as 134 (Scheme 62). Reversal of the steric course between the reactions of carbon dioxide (SE2inv) and chloroformate (SE2ret) is also observed in this system (cf. Section 8.1.21.4.3.2). Hydrolysis of the enamine products affords β-substituted aldehydes which can be further elaborated.[‌216‌,‌217‌,‌220‌,‌222‌‌224‌]

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