Tricyclo decane synthesis

The synthesis of adamantane (15), tricyclo[3.3.1.1 ]decane [281-23-2] by heating tetrahydrodicyclopentadiene (14) [6004-38-2] in the presence of aluminum trichloride illustrates another aspect of the synthetic utiHty of DCPD (80). Adamantane is the base for dmgs that control German measles and influenza (80-81) (see ANTIVIRAL AGENTS). 

The isomeric tricyclo[3.3.2.0 ]decane hydrocarbon (396) has also recently yielded to synthesis Thus, reaction of 394a with either thionyl chloride or phosphorus pentachloride led to rearrangement and formation of chloride 395a. Alternatively,... 

The construction of the tricyclo[5.2.0.02,6]nonane (26, n = 1) and tricyclo[6.2.0.02,7]decane (26, n = 2) frameworks involved the [2 4- 2] cycloaddition of readily accessible31,32 l,2-bis(trimethyl-siloxy)cyclobutene and cnone 25, n = 1 or 2, respectively.33 The yields (75-80%) were good for adducts 26a, c, e, and g. Lower yields (40-50%) were observed for adducts 26b and 26f, while adduct 26d was only isolated in a trace amount. The most interesting and important reaction, related to the total synthesis of eudesmane sesquiterpenes, was the photochemical reaction of (-)-piperitone (25g) with l,2-bis(trimethylsiloxy)cyclobutene, which gave c/.v,(5wf/u W-2/j,7/i-dimethyl-4/ -isopropyl-l f ,8Jf -bis(triniethylsiloxy)tricyclo[6.2.0.0z 7]dec-3-one (26g) with the relative cis configuration of the methyl (R2) and isopropyl (R3) groups.33,34 Some of the other photochemical [2 + 2] cycloaddition reactions utilizing l,2-bis(trimethyl-siloxy)cyclobutene are shown by the formation of 2735,36 and 28.37... 

Pyrolysis of the sodium salt of the tosylhydrazone of 10-bicyclo[5.2.1 ]deca-none provides a remarkably easy synthesis of tricyclo [5.2.1.0 4>10] decane... 

An electrochemical procedure for the replacementofcarboxyl function by an acetoxy group at the C-2 carbon atom of a tricyclo[4.4.0.01,s]decan-4-one system has been realized 90 . The procedure is utilized as the key step for the synthesis of cubebol 114... 

The first synthesis of a tricyclo[4.3.1.0 ]decane, namely of pure carbocyclic iso-twistane [G 2 X(2) = CHj, Y(7) = CHj ], was reported by Vogt S in 1968. Almost at the same time 2,7-dihetero-isotwistanes (G 2) and/or derivatives thereof became available. Today a variety of such compounds are known ... 

Similarly the bicyclic cyclopropyl ketone 134 is readily converted to the tricyclo[5.3.0.0 - ]decane 135 under similar conditions via a domino ring opening/Michael/aldol reaction sequence as shown in the Scheme 4.27 [45]. The selective attack of the iodide ion at the 6-position of 136 leading to the intermediate 137 may be due to the effective overlap between cleaved bond and the % orbital of the carbonyl group. This novel domino reaction producing polycyclic cyclobutanes was exploited for the synthesis of natural products like ( )-anthoplalone and ( )-lepidozene by the same workers [45]. 

The method of synthesis of ten-membered rings by olefin metathesis, involving tricyclo[4.4.0.0 ]decane intermediates, is also popular, and this year is illustrated by Wender and Lechleiter s synthesis of isabelin (165) (see also Section 2). 

Similarly, reductions of different racemic 2-oxabicyclo[3.2.0]heptan-6-ones [139], 2-oxabicyclo[2.2.1]heptane-7-carboxylates [140], norbomenone [102], and bicyclo[2.2.2]octan-2-one [141] have been performed the ee values, however, were moderate. For the reduction [141] of a 4-twistanone (tricyclo[4.4.0.0 ]decan-4-one), the alternative use of Rhodotorula rubra has been suggested. Kinetic resolution of racemic 5,6-epoxy-bicyclo[2.2.1]heptane-2-one using whole cells of genetically engineered S. cerevisiae allowed the synthesis of (+)-5,6-epoxy-bicyclo[2.2.1] heptane-2-ol [142]. 

In contrast to the abundant coverage of the intermolecular cycloaddition of 3-oxidopyridinium betaines [3, 87], relatively few intramolecular applications have been described. In this context, Peese and Gin have developed an efficient, asymmetric approach to the hetisine class of the C2o-diter-penoid alkaloids based on an intramolecular oxidopyridinium [5-1-2] cycloaddition in which simultaneous formation of the C5—C6 and CIO—C20 bonds in the 3-methyl-1-aza-tricyclo[5.2.1.0 ]decane core of these alkaloids was achieved [88]. As shown in Scheme 20.35, the heating of chiral oxidopyridinium betaine 81 in toluene at reflux produced the corresponding enantiopirre cycloadduct 82 in 77% yield. The latter constituted a potent intermediate for the asymmetric synthesis of the hetisine class of alkaloids, such... 

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