Acetylide Alkylation and Addition

In the remainder of this chapter, particular reactions are selected for examination of their synthetic potential. Acetylide ions are useful for linking carhon chains, particularly where a double bond is desired with stereoselectivity. Acetylene and 1-alkynes may be deprotonated with strong bases such as LDA and then treated with alkyl halides or carbonyl compounds. Preformed lithium acetylide complexed with ethylenediamine is available as a dry powder. Several alkynes derived from acetylide and carbon dioxide or formaldehyde are available, including propargyl alcohol (HC CCHjOH), propargyl bromide (HC CCH Br), and methyl propio-late (HC=CC02CH3). 

SCHEME 8.15 Retrosynthesis of cis,trans,trans- lo(leca-2J,10-tneaoic acid y-lactone. 

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