Decalin aldehyde

A key step in the total synthesis of the marine metabolite (—)-solanopyrone D (161) is the enantioselective organocatalytic intramolecular Diels-Alder reaction of the trienal (158) to the decalin aldehyde (160) in the presence of the imidazolidinone catalyst (159) (Scheme 45).187 Protonated 1,2-diamino-1,2-diphenylethane has been... 

Intermediate 40 would be produced through a coupling reaction between the appropriately functionalized decalin aldehyde 41 (available from alcohol 42) and 3-lithio-y-pyrone 23. Intermediate 42 would be formed through the strategic [2,3]-Wittig rearrangement of stannylmethyl ether 43. On the basis of the results accumulated from the nalanthalide synthesis (cf. Section Total Synthesis of (—)-Nalanthalide and Scheme 6), we expected that the C9 stereogenic center and the C8 exo-methylene function in the product 42 would be simultaneously formed. Intermediate 43, in turn, would be derived from 14 [17]. 

A-C, intermediate 90 was expected to be synthesized by a coupling reaction of the appropriately substituted decalin aldehyde 91 with 3-lithio-y-pyrone 23. Intermediate 91 would be prepared from the common intermediate 29 available from 15 (cf. Scheme 5). 

Intramolecular nitrile oxide-alkene cycloadditions also provide efficient access to six-membered rings such as cyclohexanes or decalins that are heavily adorned with functional groups and side chains. For example, this strategy was used to prepare racemic hemaldulcin (213), which is a 3,6-disubstituted cyclohexenone found in a Mexican plant that possesses a strong sweet taste. Starting from (2Z,6E)-famesal (209) (328) (Scheme 6.88), the aldehyde was treated with hydroxylamine... 

Scott Denmark of the University of Illinois reports (J. Org. Chem. 68 8015,2003) a hetero intramolecular Diel-Alder reaction of a nitro alkene 5, followed by intramolecular dipolar cycloaddition of the resulting nitronate 6, to give the tricycle 7. Raney nickel reduction effected cleavage of the N-0 bonds and reductive amination of the liberated aldehyde, to give, after acetylation, the angularly substituted cis-decalin 8. 

In a series of elegant studies, Paquette and coworkers demonstrated the potential of the Claisen rearrangement for the stereocontrolled total synthesis of natural products. Dehydrative coupling of (2)-3-(trimethylsilyl)-2-propen-l-ol with cyclohexanone (51) under Kuwajima s conditions, followed by rearrangement of enol ether (52) in decalin, led in excellent stereoselectivity (>99 1) to aldehyde (53 Scheme 8). Concise construction of the eight-membered core of acetoxycrenulidine was achieved by intramolecular phenylseleno etherification of lactone (54), introduction of the exocyclic vinyl ether double bond by selenoxide elimination and subsequent Claisen rearrangement (Scheme 9, 66% from 54). ... 

Calbistrin A (101) is a cholesterol-lowering agent (O Fig. S). Tatsuta and coworkers have realized the total synthesis of calbistrin A (101) [60]. The key synthetic Diels-Alder precursor 102 for the decalin skeleton was prepared from aldehyde 103 and two other segments shown in O Fig. 8. 

It has been shown that perfluorinated j3-diketonates are excellent catalysts for oxidation reactions in perfluorinated solvents [26]. The nickel catalyst Ni(39)2, prepared by reaction of the -diketone 39 [27] with NiCl2, catalyzes the oxidation of various (functionalized) aromatic and aliphatic aldehydes to the corresponding carboxylic acids in 76 to 87% yield in a solvent system of perfluoro-decaline and toluene at 64 °C under 02-atmosphere Eq. (16). 

Dihydridotetrakis (triphenylphosphine) ruthenium(II), RuH2 [P(Ph)3]4, exhibits excellent catalytic activity under mild conditions, transferring hydrogen from ethers, decaline, tertiary amines, and alcohols to aldehydes in about 50% yields. Coordination of the... 

The aldehyde alkene substrate 101 [Eq. (24)] was found to cyclize to an epimeric mixture of cis-decalin derivatives 102 and 103. Similarly, acyclic substrate... 

A comparison between a HAS and a PAO as stabilizers against the oxidation of PP showed that they behave differently [4]. Based on experiment showing the ability of the HAS and the PAO to reduce the oxidation rate of decalin, squalane and decalin/lauryl aldehyde mixtures, it is shown that the HAS is mainly active in the presence of aldehydes. For unstabilized PP it is shown that aldehydes play an important role in its oxidation [5]. These results are used to propose an oxidation mechanism for PP and a mechanism underlying the action of HAS. 

Oxidation of Decalin, Squalane and a Mixture of Lauryl aldehyde and Decalin [4]... 

The influence of the stabilizers mentioned in Figure 1 was studied by oxidizing three different model compounds decalin (a cyclic hydrocarbon which, like PP, contains secondary and tertiary carbons), squalane (a high molecular weight aliphatic hydrocarbon which also contains secondary and tertiary carbons), a mixture of 10% lauryl aldehyde in decalin, which could serve as a model for partly oxidized PP. All reactions were initiated with 1% of t-bulylhydroperoxide and performed at 120°C (for details see ref. 4). 

The addition of lauiyl aldehyde (10%) to decalin has a tremendous effect on the oxidation rate as well as on the effectivity of the stabilizers. This mixture already starts to oxidize while it is being heated to its final oxidation temperature (120°C), which is the reason that the data are not shown in Figure 7. In this case the effectivity of PAO-1 and HAS-1 is comparable. 

The oxidation of squalane is slower than the oxidation of the mixture of decalin and lauiyl aldehyde (compare Figures 7 and 8). Although squalane is a hydrocarbon similar to decalin, in squalane HAS are capable of reducing the oxidation rate effectively, while they were not effective against the oxidation of decalin. In squalane HAS-1 even outperformed PAO-1 (Figure 8). 

Figure 7. Influence of 0.1 wt. % stabilizer on the oxidation rate of a decalin/lauryl aldehyde mixture at 120°C. HAS-1 ( ) andPAO-1 (o). Bars show the standard deviation.

It is clear that the efficiency of the different stabilizers highly depends on the model system. PAOs are effective in all systems, but HAS are not effective in decalin. The oxidation of decalin mainly takes place at the tertiary carbon, leading to cyclodecanone and cyclodecanol [8]. This oxidation does not lead to the formation of aldehydes and acids. When aldehydes are added to decalin HAS becomes effective, so HAS is effective against the oxidation of aldehydes. HAS is also effective against the oxidation of squalane, which, like decalin, is a hydrocarbon containing secondary and tertiary carbons. However, because of its... 

The repetitive Claisen Cope rearrangement can be used as a strategy for the iterative introduction of ( )-isoprene units into a growing chain. Thus, reduction of intermediate aldehyde 44 (see above) to the corresponding alcohol 46 and treatment with acetal 40 affords a 1 1 mixture of the Claisen product 47 and Claisen-Cope product 48 in 30% yield. The tandem Claisen-Cope-Cope product 49 is obtained by heating 48 in decalin to 190°C. 

The oximes of aminoaldehydes yield the N-3 oxides of (fused) pyrimidines. Thus, several methoxy derivatives of trans-2-aminobenzaldoximes, heated at 140°C in triethyl orthoformate, gave good yields of the corresponding methoxy derivatives of quinazoline 3-oxide (88). Ultraviolet light rearranged these products to quinazolin-4-ones. (The cis forms of these aldehydes produced only benzoxadiazepines.) The same aldehydes, heated in decalin with... 

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