Chloromethyl-lithium and 1-chloro-2-methylprop-1-enyl-lithium: useful intermediates in the synthesis of unsaturated and bifunctionalized compounds

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Abstract
The reaction of in situ generated chloromethyl-lithium with ketones (5) at –78 °C afforded, after lithiation with lithium naphthalenide at the same temperature, β-oxidoalkyl-lithium compounds (6), which on reaction with electrophiles (deuterium oxide, dimethyl disulphide, carbon dioxide, cyclohexanone, and allyl bromide) yielded bifunctionalized compounds (7). When the lithiation step was carried out with lithium powder and at temperatures ranging between –60 °C and 20 °C, the corresponding decomposition of intermediates (6) derived from aldehydes and ketones (5) took place spontaneously giving the corresponding terminal or exocyclic olefins (11) regioselectively. The use of in situ generated 1-chloro-2-methylprop-1-enyl-lithium as organolithium reagent in the addition to carbonyl compounds (5) at –110 °C, followed by transformation of the resulting chlorohydrin (13) into the corresponding methyl ether (14)(successive treatment with sodium hydride and methyl iodide at 0–20 °C) gave, after lithiation with lithium phenanthrenide at room temperature, the corresponding substituted cumulenes (12).

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