1.4- diphenylbuta-l,3-dienes

The reaction of 1,4-diphenylbuta-l,3-diene (2) with trithiazyl trichloride (3) yields a bi(thiadiazole) (4), an isothiazoloisothiazole (5), a dithiazolothiazine (6), and two thiazin-odithiatriazepines (7) and (8) by 1,2-, 1,3-, and 1,4-cycloaddition reactions (Scheme 2). The bridged-mode (/3-tether) tandem inter-[4 -E 2]/intra-[3 -E 2] cycloaddition of (ii)-2-methyl-2-nitrostyrene (9) with 1-butoxypenta-1,4-diene (10) produces stable tricyclic nitroso acetals (11) which afford, after reduction and protection, highly functionalized aminocyclopentanedimethanol triacetates (12) (Scheme 3). ... 

Diphenylbuta-l,3-diene (Section Expt 6.141) is prepared by a variant of the general method in which cinnamaldehyde is similarly condensed with phenyl-acetic acid. 

Scheme 4.21 Three-component reaction of 1,4-diphenylbuta-l,3-diene, aldehydes, and diethylzinc.

Thiophenes are neither polymerized nor hydrolyzed by moderately concentrated Bronsted acids. Ring-opening demands special reagents thus, phenyl magnesium bromide in the presence of dichlorobis(triphenylphosphane)nickel(II) transforms thiophene under desulfurization into 1,4-diphenylbuta-l,3-diene ... 

Similarly, conjugated dienes, enynes, and diynes such as ( , )-l,4-diphenylbuta-l,3-diene 162, fE)-l,4-diphenyl-but-l-en-3-yne 163, or l,4-diphenylbuta-l,3-diyne 164 on treatment with trithiazyl trichloride (2 equiv) afforded the bisthiadiazole 165 in moderate to good yield (40-60%), depending on the reaction conditions (Scheme 24) <1997CC1493, 1997J(P 1)3189, 1998CC1207>. 

In contrast, l-chloro-1-fiuorobenzocyclopropene (5a) was synthesized by the general scheme from l,2,3-trichloro-3-fluorocyclopropene and buta-f, 3-diene it is extremely sensitive towards moisture.( , )-l,4-Diphenylbuta-l,3-diene underwent addition to 1,2-dichloro-... 

Nitrosyl cyanide, generated from nitrosyl chloride and silver cyanide in chloroform at —20 °C, affords unstable products with various dienes, e.g. butadiene and 2,3-di-methyl-1,3-butadiene. With methyl sorbate, compound 182 is produced (equation 103), thebaine (183) gives 184 (equation 104) and 9,10-dimethylanthracene yields the stable cycloadduct 185, which decomposes into its components on heating and consequently can serve as a source of nitrosyl cyanide. Thus heating 185 with l,4-diphenylbuta-l,3-diene gives the dihydrooxazine 186 and dimethylanthracene (equation 105). ... 

In addition, Zhou et al have developed diastereo- and enantioselective reductive coupling of 1,3-dienes, such as l,4-diphenylbuta-l,3-diene, with aromatic and heteroaromatic aldehydes by using ZnEt2 as the reducing agent and nickel complexes of chiral spiro phosphoramidites such as 21 (Scheme 4.21). In this case, the three-component reaction provided the... 

The involvement of trimethylenemethane diradicals in deazetization of diazoalkane-allene adducts or trimethylene diradicals in the deazetization of the adducts of acyclic alkenes often leads to mixture of regioisomers and stereoisomers and from the standpoint of cyclopropane syntheses, this is undesirable. Far fewer problems of this type attend deazetization of the adducts of cyclic or polycyclic alkenes and, furthermore, even a modest amount of strain in the system activates the alkene to diazoalkane addition so that there is no need for activating substituents on the double bond. Cyclopropene is highly reactive towards diazoalkanes (see also Section 1.1.5.1.5.3.1.) and cycloaddition reactions of this type provide a ready entry into the bi-cyclo[1.1.0]butane series. The addition of diphenyldiazomethane to cyclopropene gave 4,4-diphenyl-2,3-diazabicyclo[3.1.0]hex-2-ene (1), which on photolysis gave a mixture of 2,2-diphenylbicyclo[1.1.0]butane (2) and 1,1-diphenylbuta-l,3-diene (3). ... 

Direct irradiation ( = 250 nm) of the allylcyclopropane (37) yielded five products, viz. 1,1-diphenylethylene 1,1-diphenyl-2 2-dimethylethylene 1,1-di-phenyl-4-methylpenta-l,3-diene 1,1-diphenylbuta-l,3-diene and the vinyl-cyclobutane (38). Independent photolysis of the vinylcyclobutane (38) shows that it photochemically fragments into l,l-diphenyl-2,2-dimethylethylene and... 

During the investigation into temperature and ligand effects, an identifiable minor byproduct was discernible in the NMR spectrum of the crude reaction mixture post work up (in the case of Table 7.3, Entry 5). Comparison of these peaks with literature data revealed the byproduct to be (l , 3 )-l,4-diphenylbuta-1,3-diene (150) [51]. 150 must clearly arise from a homocoupling reaction of two molecules of P-bromostyrene (150), which is in competition with the transmetalla-tion step of the cyanation reaction (Scheme 7.5). 

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