Decatrien-3-ones

LP-DE also promotes and accelerates intramolecular Diels-Alder reactions of low reactive polyenones. The use of a catalytic amount of camphorsulfonic acid (CSA) further accelerates the cycloaddition and enhances the diastereo-selectivity [41]. Table 6.7 illustrates the effect of CSA on the intramolecular Diels-Alder reaction of 2-methyl-l,7,9-decatrien-3-one. 

Table 6.7 Intramolecular Diels-Alder reaction of 2-methyl-l,7,9-decatrien-3-one...

The increased stereoselectivity of decatrien-3-ones relative to the n(matrien-3-ones may also be the consequence of cooperativity between twist asynchronicity and endo stabilization that both favor the c -fused product. The decatrien-3-one transitirm state is considerably less strained than the nonatrien-3-one transition state, and the uncatalyzed decatrienone cyclizations occur at or near ambient temperature. Consequently, one expects greater endo stabilization, and hence also greater cis stereoselectivity, in the decatrienone intramolecular Diels-Alder reactions. 

The use of Lewis acid catalysis is a powerful method of increasing the rates and diastereoselectivity of many IMDA reactions. Several examples involving terminally activated nona- and deca-trienes are summarized in Tables 1 and 2. Examples illustrating rate and stereoselectivity improvements in the cycliza-timis of funcdmialized decatrien-3-ones appear in Figure The most striking of these is the... 

Speculation exists in the literature that many IMDA reactions of simple l,7,9-decatrien-3-ones, which are often generated by oxidation reactions in acidic media or are liberated in protic solvents, may be protic or Lewis acid catalyzed owing to the mildness of the cyclization conditions and the excellent stereoselectivity of their cyclizations (refs. 5h, 17, 18). The study by Gajewski cited in ref. 17c, however, establishes that the IMDA cyclization of (11) is an uncatalyzed, solvent polarity independent reaction. 

Generation of ( )-1,7.9-decatrien-3-one from ( ,T)-3-(tricthylsilyloxy)-l, 3,7.9-decatetracne under basic conditions gave exclusively the (ram-isomer, presumably as a result of base-mediated epimerization of the initially formed m-isomer21. 

A conceptually different synthetic approach to substituted derivatives of (7f)-l, 7,9-dccatrien-3-one has been described23 Reaction of silyloxycyclopropanc-containing trienes with hydrogen fluoride gave (, )-l,7,9-decatrien-3-one derivatives, which underwent intramolecular [4 + 2] cycloaddition under various conditions. 

An international inter-laboratory study recently compared quantitative methods used for measuring short chain (C10-C ) PCAs [70]. In this study, the samples to be quantified consisted of a standard solution of a commercially available PCA product containing 70% chlorine by mass (PCA-70), a synthetic PCA mixture consisting of purified products derived from the chlorination of 1,5,9-decatriene (PCA-1) and two fish sample extracts. The fish samples consisted of a cleaned up extract (lipid-free) of muscle tissue from a yellow perch fish, collected at the mouth of the Detroit River at Lake Erie, in 1995. All participating labs were asked to quantify the PCA-1 and PCA-70 mixtures and at least one fish extract against a primary standard solution which contained a known concentration of a second short chain commercial PCA product containing 60 mass % chlorine (PCA-60) and, if desired, by using other commercially available C10-C13 PCA mixtures. 

The oxidation of cxo-7-hydroxybicyclof4.3.IJdecatriene-2,4,8 (I) to bicyclo[4.3.1]-decatriene-2,4,8-one-7 (2) was effected with Collins reagent in 64% yield. ... 

The stoichiometry of the crystalline complex obtained by reaction of cyclic oligoolefins with AuCl in absolute ether at room temperature (0°C for norbornadiene) depends upon the olefin. 1,5-Cyclooctadiene and both cis,cis,trans- and oif-infrared spectra of the trienes indicate the presence of both complexed and free double bonds, the cis,cis,trans-l,5,9-cyc odo-decatriene showing one free cis unsaturation. C is,cyclodeca-diene and dicyclopentadieneform, on the other hand, only 1 1 complexes. The former olefin is complexed only at the trans double bond, whereas the latter is complexed only at the double bond in the norbomene part of the molecule (225). 

C12H17NO 2-cis-hydroxymethyl-4-trans-phenyl-1-cyclohe. .. 551.15 48.820 2 24454 C12H180 5,7-di methyl-3,5,9-decatrien-2-one 111317-19-2 524.28 46.221 2... 

Stereoselective reduction. Lithium aluminum hydride in ether reduces (1, bicyclo-[4.3.1]decatriene-2,4,8-one-7) to the less hindered alcohol (2, endo-7-hydroxybicyclo-[4.3.]]decatriene-2,4,8).4... 

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