Tetraenal, preparation

Acetoxymethyl-ds,trans,cis,trans-cyclonona-l,3,5,7-tetraene, prepared from lithium cyclononatetraenide and bromomethyl acetate at — 30 °C, was converted into 9-methylene-ci5,trans,cis,trans-cyclonona-l,3,5,7-tetraene by KOBuS Both 9-acetoxy-methyl- and 9-methylene-cyclononatetraenides were converted into the dihydro-indenes (222 R = CH2 H, CH2OAC) on warming. ... 

The indicator was prepared by the method of Oiehl and Einhorn. A solution of 5 g of sodium hydroxide in 50 mL of water and 40 ml of ethanol is prepared in a 250-mL Erlenmeyer flask. To this is added a solution of 1.64 ml (0.025 mol, 1.45 g) of acetone in 6.3 mL (0.050 mol, 5.6 g) of freshly distilled cinnamaldehyde (Note 1). This mixture is stirred thoroughly at room temperature for 30 min. The resulting voluminous yellow precipitate is filtered with suction, washed with 100 mL of water, and dried, affording 6.5 g of l,9-diphenylnona-l,3,6,8-tetraen-5-one. Recrystallization from 200 mL of hot 9511 ethanol gives 3.5 g of yellow crystals, mp 142-143 C (lit mp 142°C). This indicator is also available from Aldrich Chemical Co. 

The preparations are much simplified if a stoichiometric amount of hydrogen halide is added using an indicator to determine the end point. We have found that 1,9-diphenylnona-1,3,6,8-tetraen-5-one (dicinnamalacetone) is of appropriate basicity to detect excess anhydrous hydrogen halides in organic solvents including chloroform, dichloromethane, benzene, toluene, acetic acid, and acetone (but not in alcohols). The reaction between the... 

Heidelberger. This tetraene has evoked a eonsiderable amount of interest both as regards its eonstitution and as a primary material for polymerisation. It has been prepared again from psewdopelletierine by Cope and Overberger, ° who record m.p. -5-8 to -5-4°, 1-5342, and describe... 

Since the early work dealing with Zeise s salt, many complexes have been prepared with the formula [PtL(C2H4)X2], where L = quinoline, pyridine, or ammonia and X=C1 , Br , I, or N()2. Similar compounds have been prepared that contain other alkenes than C2H4. Many of the complexes containing dienes, trienes, and tetraenes as ligands also contain carbonyl ligands. In fact, metal carbonyls are frequently starting complexes from which alkene complexes are obtained by substitution reactions. 

The 20-membered all-E tetraene macrolide system 58 was prepared by intramolecular cyclization of vinyl stannane 59 in the presence of tris(dibenzylideneacetone)dipalladium(0) (Pd2dba3) and triphenylarsine, as shown in equation 3354. E,E-Dienamines have been... 

Other steroidal 0-(carboxymethyl)oximes which have been prepared for linkage to BSA include those of 3/3,16a-dihydroxypregn 5-ene-7,20-dione (at C-7), 3-hydroxyoestra-l,3,5(10),7-tetraen-17-one, 3a-hydroxy-5/3-androstan-17-one ( etiocholanolone ), and 17/3-hydroxyandrost-4-ene-3,ll-dione (at C-3). O-... 

The use of ring-closing metathesis for the preparation of unsaturated heterocyles is now established as a routine method for single cyclisation steps, and the method has been extended to the preparation of bicyclic systems in a single step One example is the cyclisation of the tetraene 43 leading to formation of tetrahydrooxepine 44 in 59% yield <99JOC3354>. The method is equally applicable to the formation of five- and six-membered systems. 

Derivatives of 1,2-dihydroazocine are potentially available by valence isomerization of the 7-azabicyclo[4.2.0]octadiene system. Sulfonyl derivatives (71) of the latter have been prepared, but the equilibria with dihydroazocines lie completely on the side of the bicyclic isomers (71JOC435). On heating, the bicyclooctadienes rearrange to the acyclic tetraenes (73), presumably via the unstable dihydroazocines (72). 

Using a Stille s reaction, De Lera et al. connected a tetraenic stannate with a triflate derived from the trimethylcyclohexanone [19,20]. First, the tetraenylstannate was prepared by Homer-Wadsworth-Emmons... 

The synthesis of llZ-retinal required the boronic-partner, which was prepared from 2-butyn-l-ol by addition of the tributylstannyl cuprate (83%), followed by protection of the alcohol with tBuMe2SiCl (TBDMSC1) (93%). The tributylstannyl group was substituted with boronic acid in three steps lithiation, quenching alkenyllithium with triisopropyl boronate and hydrolysis to the boronic acid. The Suzuki coupling of the C 6 tetraene with the boronic compound was carried out in THF at room temperature, in the presence of a catalytic amount of... 

Many conjugated dienes react twice with methyl 3-bromo-2-propenoate and triethylamine, making this procedure convenient for preparing a variety of dimethyl 2,4,6,8-decatetraenedioates.98 1,3,5-Hexatriene and its substituted derivatives undergo vinylation also, to form tetraenes and pentaenes in low yields.83... 

Diphenylocta-1,3,5,7-tetraene can be prepared (Expt 6.140) by condensing two mols of cinnamaldehyde with succinic acid in the presence of acetic anhydride and lead oxide, in a reaction which bears similarities with those of the Perkin type discussed above. 

Among cyclic polyenes, cyclic dienes, trienes and tetraenes have been ring-open polymerised via the metathesis reaction. Representative of the cyclodienes most commonly used for polymerisation are 1,5-cyclooctadiene, norbornadiene (bicyclo[2.2.1]hept-2,5-diene) and dicyclopentadiene as mono-, bi- and tricyclic diolefins respectively. Cycloocta-1,5-diene metathesis polymerisation is another approach to the preparation of 1,4-polybutadiene ... 

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