1.5- Dibromopentane, reaction with sodium

Now let s draw the forward scheme. 1,1-Dibromopentane is converted to 1-pentyne by reaction with excess sodium amide (to afford double elimination followed by deprotonation of the resulting alkyne), followed by aqueous woikup to protonate the terminal aUcynide. 1-Pentyne is converted to the aldehyde via hydroboration/oxidation. Subsequent reaction with sodium acetylide, followed by aqueous woikup, produces an alcohol. Reduction with H2 and Lindlar s catalyst converts the alkyne group to an alkene group. Ozonolysis converts the alkene to an aldehyde. Reaction with concentrated acid allows for elimination of the alcohol, producing the target compound. 

Pentamidine Pentamidine, 4-4 -(pentamethylendioxy)dibenzamidine (37.4.2), is made by reacting 4-hydroxybenzonitrile with 1,5-dibromopentane in the presence of sodium hydroxide to make l,5-few-(4-cyanophenoxy)pentane (37.4.1). Subsequent reaction of this with an ethanol solution of hydrogen chloride with the intermediate formation of an iminoester, and then with an ethanol solntion of ammonia gives the desired pentamidine [55-57]. 

Diesters.—Phase-transfer conditions, using aqueous carbonate as base, have been found for effecting Michael additions of malonic esters and acetoacetates to a,/3-unsaturated aldehydes yields vary between 44 and 65%. Monoalkylated material is obtained as the sole product (43% yield remainder starting material) from the reaction of dimethyl malonate with 1,5-dibromopentane when alumina pre-treated with NaOMe is used as base/ When more of the base is employed, only the intramolecular cyclization product is formed. A new approach to the mono-alkylation of malonates is use of the stable, non-hygroscopic sodium salt... 

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