Preparation and Selected Reactions of 2,3-Bis(bromomethyl)-1,3-butadiene

Article abstract of DOI:10.1021/jo01293a021

2,3-Bis(bromomethyl)-1,3-butadiene (1) was prepared by zinc-induced debromination of 1,4-dibromo-2,3-bis(bromomethyl)-2-butene (2).The versatility of 1 as a synthetic intermediate was demonstrated through consecutive use of its allylic bromides and conjugated diene functions, with eventual further modification of the primary reaction products.Coupling of 1 with vinylmagnesium chloride or ethynylmagnesium bromide gave highly unsaturated hydrocarbons (8-11).Reaction of 1 with nucleophiles such as sodium methoxide, sodium azide, sodium acetate, or potassium cyanide gave symmetrically disubstituted 1,3-butadienes ( 12a-d) which could in some cases be modified at the level of the substituent into other analogous dienes (12e-f).Five-membered heterocycles with exocyclic cis-fixed dienes, namely, the thiolane 13, oxolane 14, and pyrrolidines 15a-e were obtained from 1 by reaction with sodium sulfide, with potassium hydroxide, or with secondary amines, respectively.Two of the pyrrolidines (15a,c) were photolytically cyclized into the corresponding 3-azabicyclo<3.2.0>heptene derivatives (24a,b).Dimethylenehexahydropyridazine derivatives (28,29) were obtained from 1 by reaction with dimethyl azodicarboxylate and subsequent elimination of bromine.These unstable compounds could be stabilized as diene-iron tricarbonyl complexes (31-34).Carbocyclic systems were obtained from 1 by various Diels-Alder additions, such as the addition of dimethyl acetylenedicarboxylate which was followed by debromination and addition of a second molecule of the acetylenic ester to give a tetrahydronaphthalene derivative (35 -> 36 -> 37).Reaction of 1 with diiron nonacarbonyl produced three binuclear ? complexes: the known 2,2'-bis(?-allyl) complex (38) and two isomeric trimethylenemethane-type complexes (39,40) d eriving from dimerization of 1.The structure of the latter was proven by isomerization into bis(diene) complexes (41,42) and oxidation to known hydrocarbons.