Morphinans dienones

Sz ntay et al. [36) succeeded in a biomimetic synthesis of ( )-salutari-dine (52) in 2.7% overall yield from ( )-reticuline (51) with the aid of LTA oxidation conducted in CH2CI2 in the presence of trichloroacetic acid, with ( )-isoboldine (35) also being formed (Scheme 7). Since morphinan-dienone 52 (65) is an important precursor to morphine, the above synthesis is quite interesting in spite of the low yield. 

Some years ago a general synthetic method 52) for the morphinan-dienone-type alkaloids was discovered by modifying the Pschorr reaction which had been used widely for the synthesis of the aporphine alkaloids and this method was applied to a synthesis of the homo-morphinandienone-type compounds. 

Recently, the reaction was applied to the syntheses of morphinan-dienone-, homomorphinandienone-, and homoaporphine-type compounds. 

The biosynthesis of cularine alkaloids (239) by phenolic oxidation also proceeds via the dienone compound (Scheme 4) similar to the aporphine or morphinane alkaloids. 

Alkaloids of the morphinane group. If the tetrahydroisoquinoline alkaloid norlaudanosoline is written in such a way that part of the molecule is rotated around the dotted line (Fig. 280), the relationship to the morphinane-type alkaloids becomes obviously. The actual precursor of these compounds, however, is (R)-reticuline. It is probably attacked by a phenol oxidase (C 2.3.1) yielding a biradical which is stabilized by the formation of the dienone (- -)-salutaridine. After reduction of (-j-)-salutaridine closure of a new 0-heterocyclic ring results in the formation of thebaine. The alkaloids codeine and morphine are synthesized from thebaine in Papaver somniferum,... 

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