3.3- Diaryl-2-propen

A stepwise Stille reaction enables the synthesis of unsymmetrical 3,3-diaryl-2-propen-l-ol derivatives. The first reaction occurs by replacement of the (Z)-substituted stannyl group of 3,3-bis(tributylstannyl)allyl methoxymethyl ether. ... 

Bao and co-workers demonstrated a CDC reaction between 1,3-diaryl-propenes and 1,3-diketones in the absence of metal catalyst using DDQ (2,3-dichloro-5,6-dicyano-l,4-benzoquinone) as the oxidant. The reaction proceeded smoothly under very mild conditions and gave the corresponding products in good-to-excellent yields (Scheme 5.7). °... 

Bromination of the methyl group of (249) with A -bromosuccinimide, followed by reaction with excess secondary amine gave (250) which shows combined analgesic and antitussive properties. The Reformatsky reaction has also been used for the preparation of 2-amino-ethyl 3,3-diaryl-3-hydroxypropanates (251) as well as their dehydration products. The propene amides (252) have also been prepared for pharmacological evaluation. In l-methyl-3-bis (2-thienyl)-... 

Chalcones (l,3-diaryl-2-propen-l-ones) are open-chain fiavonoids that are widely biosynthesized in plants. They are important for the pigmentation of flowers and, hence act as attractants to the pollinators. As fiavonoids, chalcones also play an important role in defending against pathogens and insects. A review of the literature concerning the evaluation of natural chalcones from medicinal plants reveals that many studies into their antimicrobial and antiviral activities have been carried out in recent years. Some of these compounds were isolated by bioassay-guided fractionation, after previously detecting activity on the part of the plants. 

Benzo[6]thiophene 1,1-dioxides have been made by cyclization procedures (Section 3.15.3.1.7). Homologs of acetophenone cyclize on treatment with chlorosulfonic acid to give 2-substituted 3-chlorobenzo[6]thiophene 1,1-dioxides (equation 86). Similarly 1,1-diaryl-1-propenes in concentrated sulfuric acid gave 2-methyl-3-arylbenzo[6]thiophene 1,1-dioxides (65JOC2840). Friedel-Crafts cyclization of l,l-diphenylethylene-2-sulfonyl chloride gave 3-phenylbenzo[6]thiophene 1,1-dioxide (equation 87) (59JA2000). Treatment of various biphenyl derivatives with fuming sulfuric acid forms the dibenzothiophene 5,5-dioxides (Section 3.15.3.1.7). 

Whereas diaryl ditellurium compounds and copper powder in refluxing dioxane yielded diaryl tellurium derivatives (p. 419), bis[3-chloro-2-acyloxypropyl] ditellurium compounds lost both tellurium atoms under these conditions. The tellurium-free products were propenes. During the reaction the acyloxy group migrated to take the place of the chlorine atom5. 

The reaction of 2,3-diaryl-l-ethoxycyclopropenylium ions 10 with arylmaiononitriles in the presence of a tertiary amine first provided the 1,2-diaryl-3-(aryldicyanomethy )-3-ethoxycyclo-propenes 11 in moderate to good yields. These adducts gave the dicyanoquinodimethanes 12-15 upon heating at around their melting points, probably via a dissociation-recombination involving elimination of ethanol. ... 

Chalcones (l,3-diaryl-2-propen-l-ones) are flavonoids lacking a heterocyclic C ring. Also this category of flavonoids displays a broad spectrum of bio activities such as anticancer, antifungal, antibacterial, antiviral, and anti-inflammatory properties (Calliste et al. 2001). Dihydrochalcones, which do not have a P double bond, comprise phloretin [P- (4-hydroxyphenyl) -1 -(2,4,6-trihydroxypropiophenone) and its glucoside, phlo-ridzin (phloretin 2- P-D-glucose). Comparison with structurally related compounds revealed that the antioxidant pharmacophore of phloretin is 2,6-dihydroxyacetophenone (Rezk et al. 2002). The po-... 

We look at these reactions in detail in Sections 11.3 and 6.6, respectively. For the moment we need only note that the p-C—H of these cyclic dialkyls is held away from the metal and so is not available for p elimination. The P C—C bond is held close to the metal, however, and so these rearrangements are really p eliminations involving a C—C, rather than a C—H, bond. The reaction of Eq. 3.21 is of particular significance because it is the key step of an important catalytic reaction, alkene metathesis, which converts propene to butene and ethylene (Chapter 11). The anion of [Li(tmeda)]2[(CH2)4-Pt(CH2)4] contains two tetramethylene rings bound to square planar Pt(II) and is thermally rather stable. Cyclic diaryls are rare an interesting and very stable example is shown below ... 

Chalcones, l,3-diaryl-2-propen-l-ones, belong to the plant flavonoid family. The name chalcone comes from a Greek word chalcos (bronze). Chemically, they consist of open-chain flavonoids in which the two aromatic rings (A and B) are joined by... 

Miscellaneous Reactions. Bromodimethylborane can also be used to convert dialkyl, aryl alkyl, and diaryl sulfoxides to the corresponding sulfides (eq 15). Typically, the sulfoxides are treated with 2.5 equiv of Me2BBr in dichloromethane at —23 °C for 30 min and at 0°C for 10 min. Bromine is produced in the reaction and must be removed in order to avoid possible side reactions. This is accomplished by saturating the solution with propene prior to introducing the reagent or by adding cyclohexene. Phosphine oxides and sulfones failed to react under the conditions used to deoxygenate sulfoxides. 

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