Cinnamaldehyde, reaction with Wittig

ChOLESTANE, 30-METHOXY-, 41, 9 Cholestanol, etherification of, 41, 9 Cholestanyl methyl ether, 41, 9 Cinnamaldehyde, reaction with Wittig reagent, 40,86... 

Maleic anhydride is a convenient dienophile because of its rapid reaction with most dienes as well as its stability and ease in handling (although it is poisonous). The diene for this reaction, 1,4-diphenyl-1,3-butadiene, is readily prepared by the Wittig reaction with benzyltriphenylphosphonium chloride and cinnamaldehyde (Chapter 11, Section I). 

Syntheses by Sakakibara and associates (112) was based on substituted arylpropanoic acids (139) which were transformed in several steps into the ylide (140). Wittig reaction with substituted cinnamaldehydes gave the enones 141. In this way several natural diaiylheptanoids were synthesized (17, 81). 

The condensation of the cinnamaldehyde derivative (18) with ethoxycarbonyl-pentyltriphenylphosphorane in DMF gave a mixture of tram-trans- and trans-cis-products.22 A general method to prepare l-substituted-m-9-alkenes (19), using a stereoselective Wittig reaction, has been described.23 2,2-Dimethyl-3-butenal (20)... 

Prelab Exorcise Account for the fact that the Wittig-Horner reaction of cinnamaldehyde gives almost exclusively the E, E-butadiene with very little contaminating E,Z-product. 

The reagent is useful because the Wittig reagent (C6H5)3P=CHCHO and the usual phosphonate reagent (C2 H 5 0)2 P OCH 2 C H (O C2 H.-,), do not react with ketones. Moreover, the reaction proceeds stereoselectively to give the trans olefin thus benzaldehyde affords cinnamaldehyde in 11% yield. 

Wittig-type reaction. The reagent reacts with benzaldehyde in liquid ammonia to give a mixture of enynes (2) and (3). Cinnamaldehyde, also expected to give a mix-... 

Assuming pressure-dependent diastereoselectivity to be primarily caused by differences in steric interaction of the two diastereomeric transition structures and not by a change in reaction mechanism, an increase in — AAV with increasing bulkiness of the substituents and was anticipated. The dienes 93a-c were prepared in a three-step sequence starting from trans-cinnamaldehyde by alkylation, oxidation and Wittig reaction. The cycloadditions were carried out in toluene... 

The Ni-catalyzed olefination of aromatic aldehydes and cinnamaldehyde with alkylzinc reagents proceeds smoothly in the presence of MesSiCl [118]. Unlike the Wittig reaction, this reaction achieves high E selectivity. A plausible mechanism consists of three steps the Zn-Ni transmetalation between an alkylzinc and the nickel catalyst, the MesSiCl-mediated addition of the resultant alkylnickel... 

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