Perhydrophenanthrene

This example aside, the utility of the electrohydrocyclization reaction in the assembly of natural products remains essentially untapped. The reason for this observation is not entirely clear. Consider, for example, the rapid and efficient construction of the perhydrophenanthrene skeleton as exemplified by the conversion illustrated below [18]. The reaction is stereospecific, leading to the trans-anti-trans ring fused adduct 13 in a 65 to 72% yield. It takes little thought to imagine the application of this powerful transformation to the synthesis of steroids. Yet, this opportunity has not b n realized. 

On the other hand, the formation of the perhydrophenanthrene system instead of the linear anthracene system is favored by the fact that cjs-decalones form almost exclusively the A -enolate (according to the conventional numbering of decalins) and consequently alkylation takes place selectively at C(10) instead of C(6) (according to the conventional numbering of steroidal systems). 

A 13C-NMR study645 on the stereochemistry of perhydronaphthaleno[2,l-e]pyrido[l,2-c -[l,3]oxazines 5 was based on comparisons with bi- and tricyclic hydrocarbons (bicy-clo[4.4.0]decanes and perhydrophenanthrenes) and related heterocyclic analogs, such as quino-lizidine 6 and perhydropyrido[1,2-c][l,3]oxazine 7. 

Polycyclic hydrocarbons.5 Perhydrogenation of 2,7-dialkyl-9,10-dihydro-phenanthrenes (1) with Pd/C as catalyst at 200° under pressures of 120-170 atm. results in the all-trans-perhydrophenanthrenes (2). A similar hydrogenation (Pd/C, HC104) converts 2,6-dialkylnaphthalenes (3) into trans-dialkyldecalins (4). 

Over Raney Ni, phenanthrene may be hydrogenated to 1,2,3,4-tetrahydro-, s- and as-octahydro-, dodecahydro-, and perhydrophenanthrenes under the conditions described in Scheme 11.19.260... 

Perhydrophenanthrene (Z)-5-Chloro-4-pentenoic acid (1Z,4 )-1,2,4,5-Tetrachloro-1,4-pentadiene... 

The perhydrophenanthrene (PHP) sample was specially prepared for the present tests by two-stage catalytic hydrogenation of pure phenan-threne in a proprietary process. Analysis of the PHP sample showed it to contain 95.7 wt % perhydrophenanthrene with 4.3 wt % octahydro-phenanthrene the main impurity no residual phenanthrene could be detected. The measured hydrogen content of the PHP sample, 12.54 wt % H, accorded closely with the value independently estimated from the foregoing sample composition. The isomer distribution within the PHP... 

Abbreviations as follows (CYH) cyclohexane, (DHN) decahydronaphthalene (mixture of two isomers, approx 53% trans), (PHP) perhydrophenanthrene (mixture of isomers, distribution unknown). 

Figure 3. Pyrolysis pathways for perhydrophenanthrene sample (PHP). ( a) Perhydrophenanthrene, (b)...

If the retrosynthesis of a target compound leads to two symmetrical fragments, the Kolbe electrolysis is a favorable method for its synthesis. For example, the dimerization of L or LI is the key step in the synthesis of pentacyclosqualene [192] and of or-onocerin [193], respectively. Similarly, the precursor of a perhydrophenanthrene has been synthesized [194a]. 

Sugimoto K, Tamura K, Tohda C, Toyooka N, Nemoto H, Matsuya Y (2013) Structure-activity-relationship studies on dihydrofuran-fiised perhydrophenanthrenes as an anti-Alzheimer s disease agent. Bioorg Med Chem 21 4459 471... 

The synthesis of perhydrophenanthrenes related to tri- and tetra-cyclic diterpenoids has continued to be an active area.167 Compound (94) has been synthesized as a possible intermediate for the synthesis of cafestanone.168 A synthetic approach to diterpenoids with an abnormal trans-syn ab ring junction [e.g. (95)] has been described.169 The syntheses of 13-methoxypodocarpatrien-19,20-dioic acid170 and the ll-hydroxyabieta-2,8,11,13-tetraen-l-one,171 isomeric with shonanol, have been described. 

Weibel, J.-M., and Heissler, D., A new access to trans-syn-trans perhydrophenanthrenic systems. Synthesis of (9P77)-8 -methylpodocarpan-13-one, Tetrahedron Lett., 35, 473, 1994. 

Ethyl perhydrophenanthrene Ethylene glycol Ethylene glycol ether Ethylene glycol, inhibited Ethylene oxide Ethylene, made in chemical plants... 

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