3- PHENYL-4-PENTENAL

C. 3-Phenyl-4-pentenal. In a 100-mL, round-bottomed flask equipped with a magnetic stirring bar is placed 20.1 g (0.098 mol) of (E)-3-[(E)-3-phenyl-2-propenoxyjacrylic acid from B (Note 13). The flask is fitted with a distillation head for vacuum distillation and heated at 0.1 mm pressure. The oil bath temperature is maintained between 160-165°C while the mixture is stirred, until all the material melts. Once the initial reaction is under control the oil bath is slowly heated to 180°C. The product is collected in a receiver flask cooled with a dry ice-acetone bath to give 13.3-14.3 g (84-91% yield) of 3-phenyl-4-pentenal, bp 114-115°C (15 mm) (Note 14). 

C. 3-Phenyl-4-pentenal. In a 100-mL, round-bottomed flask equipped with a magnetic stirring bar is placed 20.1 g (0.098 mol) of E)-3-[(E)-3-phenyl-2-propenoxy]acrylic acid from B (Note 13). The flask is fitted with a... 

Oxopentanals may be synthesized from allylic alcohols by 3,3 sigmatropic rearrangement of their vinyl ethers, and subs uent oxidation of the terminal double bond. Cinnamyl alcohol (31) was converted to the allyl vinyl ether (32), which was subjected to Qaisen reairangement to give 3-phenyl-4-pentenal (33) in 50% yield. Oxidation of the terminal double bond of (33) gave 3-phenyl-4-oxopentanal... 

The Bosnich group explored the kinetic resolution of 3-phenyl-4-pentenal 13 via an asymmetric hydroacylation reaction. Itwas found thatwhen [Rh((S)-BINAP)]C104 was utilized, the cyclization product 14 could be afforded in 51% yield and 48% ee, along with the side product 4-phenyl-4-pentenal 16... 

Scheme 8.6 Kinetic resolution process in the cyclization of 3-phenyl-4-pentenal reported by Bosnich.

Ebenfalls iiber einen Dreiring (Bis-[benzyliden]-cyclopropanon) verlauft die Reduktion von 2,4-Dibrom-3-oxo-l,5-diphenyl-l,4-pentadien in DMF [isoliert wild3-Oxo- 1,5-di-phenyl-penten-(4)-in-( 1)]. In Methanol hingegen bildet sich 5-Oxo-2,3-diphenyl-cydo-penten3. 

Franke, A., Mattern, G.. and Traber, W., Synthetical juvenile hormone. Part 4. pfiira-Substituted 2-methyl-5-phenyl-penten(l)-carboxylic acid derivatives, Helv. Chim. Acta, 58, 293, 1975. 

Phsiiyl-penten-(2) 6, 497. 8-Phenyl-penten-(l) 6, 497, II 392. 8-Methyl-l-phenyI-buteo-(l) S II392. 

Methyl-6-phenyl-hexen-(5)-oI-(4) 6 II 550. 5.0n-4.4-djmetnvl-5-phenyl-penten.(l)... 

Ci4H N40j 1 -[6-0xy-3-metl l-phenyl]-penten-(4)-dion-(1.2)-disemicarbazon 8 0340. 

Kperimno-l-[3.4-methylendH>xy-phenyl]-penten-(l )-on (3)-pheny/hy<2rason 1162. 

Fhenyl-1.6-bis.[4-eblor.phenyl]-penten.(2).dion-(1.5) 7 II771. 

Diphenyl-3- [2-aoetoxy-phenyl]-penten.(2)>dion-(l.S) 8 II426. 

LS,4.S )-(E)-2-Bromo-4-l(2-methoxyethoxy)methoxy]-l-phenyl-2-penten-l-ol (3 A, R = C6H5 R2 = II) Typical Procedure49 ... 

The addition to 2-cyclohexcnone or (fj-d-phenyl-S-penten -one gave products with d.r. 99 1. Since the configuration of 5 was not determined, a detailed interpretation of the stereoselectivity is not possible. The 1,4 addition of the chiral cuprate reagent, lithium [2-(l-dimethylamino-ethyl)phenyl](2-thienyl)cuprate, to ( )-2,2-dimethyT5-phenyl-4-penten-3-one produced predominantly one diastereomer with d.r. 99 1, while the 1,4-addition of [2-(l-dimethylaminoethyl)-phenyl]lithium to the same enone gave predominantly the opposite diastereomer (d.r. 3 97). 

The addition of methyllithium to -alkoxy-a-(trimethylsilyl)-of/ unsaturated sulfones, 3-alkoxy-5-phenyl-l-phenylsulfonyl-l-(trimethylsilyl)-l-pentene and subsequent desilylation gives syn-products. The syn to anti diastereoselectivity is generally high and essentially independent of the nature of the y-alkoxy substituent8-13. 

Dagegen reagiert 5-Phenyl-pentadien-(2,4)-saure-methylesterin einer 1,6-Addition zu 5-Phenyl-6-oxo-hep-ten-(2)-sdure-methylester (15% d.Th.)3 und unter 1,4-Addition zum 5-Phenyl-3,3-diacetyl-penten-(4)-sdure-methylester (30% d.Th.). 

We initially tested Candida antarctica lipase using imidazolium salt as solvent because CAL was found to be the best enzyme to resolve our model substrate 5-phenyl-l-penten-3-ol (la) the acylation rate was strongly dependent on the anionic part of the solvents. The best results were recorded when [bmim][BF4] was employed as the solvent, and the reaction rate was nearly equal to that of the reference reaction in diisopropyl ether. The second choice of solvent was [bmim][PFg]. On the contrary, a significant drop in the reaction rate was obtained when the reaction was carried out in TFA salt or OTf salt. From these results, we concluded that BF4 salt and PFg salt were suitable solvents for the present lipase-catalyzed reaction. Acylation of la was accomplished by these four enzymes Candida antarctica lipase, lipase QL from Alcaligenes, Lipase PS from Burkholderia cepacia and Candida rugosa lipase. In contrast, no reaction took place when PPL or PLE was used as catalyst in this solvent system. These results were established in March 2000 but we encountered a serious problem in that the results were significantly dependent on the lot of the ILs that we prepared ourselves. The problem was very serious because sometimes the reaction did not proceed at all. So we attempted to purify the ILs and established a very successful procedure (Fig. 3) the salt was first washed with a mixed solvent of hexane and ethyl acetate (2 1 or 4 1), treated with activated charcoal and passed into activated alumina neutral type I as an acetone solution. It was evaporated and dried under reduced... 

Diese Vermutung lieB sich durch Synthese bestatigen (197). Oxy-dative Kupplung von Phenylacetylen (LXII) mit cis- (XIII) bzw. trans-Penten-(3)-in-(l) (XXVI) fiihrte zu den cis-trans-isomeren Phenyl-diin-enen, von denen die trans-Verbindung (LXI) mit dem Naturstoff im UV-Spektrum, Amax=3l8 297,5 279,5 264,5 252,5 241 mp (e = 19 300, 22 650, 18200, 11 750, 26 900, 29 000) (in Athanol), identisch war. 

We have developed an assay to identify peroxidase reducing substrates based on their ability to stimulate reduction of 1-hydro-peroxy-5-phenyl-4-pentene (Equation 5) (39). The hydroperoxide is... 

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