Decalin derivatives reactions

Scheme 29 Tandem benzannulation-Mitsunobu reaction of a chiral decalin-derived carbene complex...

The mechanistic and synthetic groundwork has been unequivocally established for the consecutive cycloreversion transannular ene reaction sequence, from which /ra/w-decalin derivatives with a hydroxyl group at the ring junction are produced.146,147 As an example, the thermally induced cycloreversion of the ester 43 at 200°C affords 45 in an astonishing 96% yield.146 Presumably the initial cycloreversion product 44 is converted by a transannular ene reaction to generate the decalin 45.146 However, not all the cycloreversion reactions proceed to give a single product as predicted, as can be shown by the examples collected in Table 7. In fact, closer inspection of work already reported has shown that complex product mixtures are usually obtained from cyclobutane cycloreversion reactions.143,148 152... 

The palladium-catalyzed arylation and alkenylation of olefins, which were first discovered in the 1970 s by Heck (7,2) and Mizoroki (3) and have been often called the "Heck reaction", are versatile synthetic means for making a carbon-carbon bond. These reactions have been extensively used for organic synthesis during the past two decades (4-7). However, no reports on the "asymmetric Heck reaction" have been appeared until very recently. Shibasaki reported an asymmetric intramolecular cyclization of alkenyl iodides to give c/j-decalin derivatives of 80-91% ee (8-10). Overman reported an intramolecular cyclization of alkenyl triflate, giving a chiral quaternary carbon center of 45% ee (77). We report herein the first example of intermolecular asymmetric Heck-type arylation of cyclic olefins catalyzed by (7 )-BINAP-coordinated palladium complexes (Scheme 1) (12,13). 

The famous ligand BINAP controls an intramolecular Heck reaction to give decalin derivative... 

A Lewis acid-mediated two-fold asymmetric Michael addition allows access to c( s-decalin derivatives. The reaction of the trimethylsilylenol ether of acety Icyclohexene with phenylmenthyl acrylate in the presence of Diethylaluminum Chloride (eq 7) yields the decalone in 64% yield (70% de). This has been shown not to be a Diels-Alder reaction. If the reaction is worked-up early, the initial Michael adduct can be isolated. ... 

The famous ligand BINAP controls an intramolecular Heck reaction to give decalin derivatives with good enantiomeric excess. BINAP is the optically pure phosphine built into the palladium catalyst. The presence of silver ions accelerates the reaction as well as preventing double bond isomerization in the original substrate. This time the chiral ligand selects which double bond is to take part in the reaction. The vinyl palladium species is tethered to the alkene and can reach only the same face. The faces of the alkenes are diastereotopic but the two alkenes are enantiotopic and you must know your right from your left to choose one rather than the other. 

Alcohol dehydrogenase from pig liver (/ e-face selective), from Mucor javanicus (Si-face selective), and, especially, from horse liver (/fe-face selective) can be used for the reduction of cyclic ketones. The horse liver enzyme is very well characterized and models for the prediction of the stereochemical course of the reaction have been developed278,279. When subjected to horse liver alcohol dehydrogenase (HLADH) reduction, the following decalin derivatives yield products with >98% ee279,280. e.g. ... 

Sato, Y., Sodeoka, M. and Shibasaki, M. (1990) On the role of silver salts in asymmetric Heck-type reaction. A greatly imrpoved catatytic asymmetric synthesis of cis-decalin derivatives. 

In general, these compounds were synthesized from appropriately substituted and selectively protected phenolic esters. A reaction sequence that consisted of selective deprotection, oxidation to the quinoid system, and addition of an amino acid gave vinylogous esters. Linkage to the trans-decalin building blocks with an exocyclic double bond was achieved with a Suzuki coupling of substituted arylboronic acids to the corresponding decalin-derived vinyl bromides. Reduction of... 

The occurrence of carbocationic intermediates in the Hofer-Moest variant of the Kolbe reaction can lead to numerous rearrangement processes. For example, electrolysis of carboxylic acid 68 in methanol results in the oxidative ring opening of the norbomane skeleton[30]. In a similar manner, GroB-type fragmentation of the decaline derivative 70 affords the 10-membered-ring ketone 71 in good yield (Scheme 12) [31]. 

The sequential ene reaction annelation sequence has been shown to be applicable to 2- and 3-substitutedmethylenecycloalkanes.33 Methyl groups in the 2-position are transformed into angular methyl groups in decalin or indane derivatives. Reaction of 2,6-dimethyl-methylenecyclohexane (84) with acrolein and Me2AlQ gives 86 in 69% yield and 88 in 12%yield... 

We have thus developed a viable entry utilizing the intramolecular Diels-Alder reaction to assemble a tricylcic ring system which can be cleaved open to the decalin ring system of the Clerodane diterpenes. The approach should also make available highly functionalized decalin derivatives which might he useful for syntheses of other natural products containing a decalin skeleton. 

More recently, the Heck reaction has been used in cascade cyclisations, and under enantioselective conditions. For example, the intramolecular synthesis of decalin derivative 9 has been achieved in good enantiomeric excess, using an optically pure phosphine (Binap) as part of the palladium catalyst. ... 

Ohrai K, Kondo K, Sodeoka M, Shibasaki M. Effects of solvents and additives in the asymmetric Heck reaction of alkenyl triflates catalytic asymmetric synthesis of decalin derivatives and determination of the absolute stereochemistry of (+)-vemolepin. J. Am. Chem. Soc. 1994 116(26) 11737-11748. 

Thermodynamic parameters have been obtained from kinetic HNMR spectroscopic studies of the thermal decomposition of ethyl 2,7-di-to7-butyl-5-methylthiepin-4-carboxylaten and two 1-benzothiepin compounds.12 The activation parameters for sulfur extrusion are AH = 93.7 kJ mol - 1 and AS = — 112.6 J Kmol-1 (in [2H18]Decalin) for the thiepin derivative,11 and AH = 75.3 and 87.9 kJ mol1 and AS = —100.4 and —104.6J Kmol-1 (in [2Hs]toluene) for the benzothiepin compounds.12 The large negative activation entropy values are consistent with a high degree of order in the anticipated thianorcaradiene transition state of the sulfur extrusion reaction. 

Thermal rearrangement of 2-vinylaziridine 203, with an electron-withdrawing substituent on the nitrogen atom, at reflux in decalin predominantly yielded 2-pyr-roline 204 along with some 3-pyrroline derivatives 205 (Scheme 2.50) [79]. A similar reaction was also observed with l-alkyl-2-phenyl-3-vinylaziridines 206 [80]. From these observations, the nature of the products formed depends on the natures of the substituents on the aziridine ring if the ring carbon carries a phenyl substituent, the thermolysis in most cases preferentially yields 2-pyrrolines. 

---