Dihydrophenanthrene derivatives

Rycroft et al. (1999) identihed the major components of plants from six locations in western Scotland and four from the Azores using nuclear magnetic resonance (NMR) fingerprinting and GC-MS. The terpene P-phellandrene [129], which may be responsible for the aroma of material crushed in the held, was detected in all specimens. The major components, which appear in Fig. 5.6, were shown to be methyl eveminate [444], the four methyl orcellinate derivatives [445 8], the two 9,10-dihydrophenanthrene derivatives [449] and [450], the newly described phthalide killamiensolide [451], and the bibenzyl [453]. Methyl eveminate was the major compound in all 10 specimens other compounds were more varied in their occurrence. Killamiensolide was not isolated as such but was detected when extracts were acetylated yielding, among other compounds, [452]. The presence of the bibenzyl compound [453] in more than trace amounts in P. killarniensis raises the possibility that it represents contamination from P. spinulosa with which it was growing at the one site. 

Fig. 10.4 More examples of 3-20-KIE s. (Top, solvolysis of a t-butyl substituted adamantine. Bottom, racemization (loss of optical activity) of a dihydrophenanthrene derivative (Mislow, K., and coworkers, J. Am. Chem. Soc. 86, 1733 (1964))...

Erwahnt sei femer die iiber Dihydrophenanthren-Derivate verlaufende photochemische Cyclisiemng von Stilbenen zu Phenanthren-Derivaten (fur Lit. vgl. (186)). 

Cis-stilbenes, which are easily obtained from their trans-isomers by trans, cis-photo-isomerization, can give rise to dihydrophenanthrene derivatives upon direct irradiation (Scheme 9.17). The latter compounds are easily converted into phenanthrenes under oxidizing conditions (oxygen, I2, or rc-electron acceptors such as tetracyano-ethene) [24]. 

Dihydrophenanthrene synthesis. Evans et al. have reported a new route to dihydrophenanthrene derivatives based on the condensation of p-quinone mono-ketals (1) or monosilyl cyanohydrin derivatives (5, 721-722) with the enolate of methyl 3-(3,4,5-trimethoxyphenyl)propionate (2) to give p-quinol ketals (3). These undergo acid-catalyzed cyclization to dihydrophenanthrene derivatives (4). A typical example is formulated in equation (I). The choice of the Lewis acid catalyst is sometimes critical for the cyclization. In the case of the cyclization shown above, use of SnCL, CF3COOH and BF3 etherate resulted in much lower... 

Several radical intermediate-based methodologies have been introduced for decarboxylations as an extension of earlier efforts on the deoxygenation of alcohols. One of the early approaches involved the TBTH reduction of the dihydrophenanthrene derivative of carboxylic acids (equation 71). However, the difficulties associated with the preparation of the phenanthrene ester derivatives and lack of success with tertiary carboxylic acids proved to be disadvantageous. A more notable discovery in this context is the demonstration that esters derived from COOH groups attached to primary, secondary and tertiary carbons and iV-hydroxypyridine-2-thione undergo efficient reductive decarboxylation in the presence of TBTH in refluxing benzene or toluene... 

Fig. 312. Structural formulas of some dihydrostilbene and dihydrophenanthrene derivatives...

Cheng et al. have demonstrated the [2+2+2] cocyclization of two arynes with bicyclic alkenes giving the corresponding norbomane anellated 9,10-dihydrophenanthrene derivatives 105. The reaction probably proceeds by initial formation of a palladacycle from one aryne molecule and the... 

In this field, Cheng et al. have also developed the carbocyclization reaction of aromatic iodides, bicyclic alkenes, and arynes to afford various armulated 9,10-dihydrophenanthrene derivatives 117 (Scheme 12.58) [102]. A related eross-coupling of arynes with aryl iodides but using alkynes as the third component has been described by Larock and Liu, furnishing substituted phenanthrenes 118 (Scheme 12.58) [103]. 

Another interesting example reported by this group consists of the palladium-catalyzed carbocyclization of aryl iodides, bicyclic alkenes, and arynes. Annulated 9,10-dihydrophenanthrene derivatives 26 are obtained through a mechanism that involves C—H activation promoted by the fluoride anion as the key step [37], On the basis of the regio-chemistry of the products obtained and supported by the isolation of complexes similar to those involved in the process, the authors propose the catalytic cycle depicted in Scheme 3.18. 

Sato and co-workers described the nickel-catalyzed [2+2+2] cycloaddition of arynes and an unactivated alkene allowing for the preparation of 9,10-dihydrophenanthrene derivatives, resulting from the reaction of two arynes with an unsaturated part of a a,co-diene in the presence of an excess... 

Table 1. 4a,4b-Dihydrophenanthrenes. Systems derived from Stilbenes...

Table 2. 4a,4b-Dihydrophenanthrenes bridged at position 4 and 5, derived from 12.2)metacyclophanes...

Table 6. 4 a,4 b-Dihydrophenanthrenes with 6-9 conjugated rings, derived from 1,2-diarylethylenes... 

Table 8. 4a,4b-Dihydrophenanthrenes with 7 conjugated rings, derived from bianthrones...

Table 14. Ring opening and fluorescence quantum yields of iJ-naphthylethylene- derived 4a,4b-dihydrophenanthrenes 2+-26)...

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