Endiandra introrsa

Polycyclic endriandric acid A-like Endiandra introrsa C.T. White, Lauraceae, Ang. from Australian foests MI). Macrolides ervthromvcin-like erythromycin Streptomyces erythreus, Actinom., Bact. from the Philippine soil and picromycins, from temperate soil MI). 

Reduction-triggered pericyclic reaction has been used for the biomimetic total synthesis of endiandric acids A-G [72]. Endiandric acids are polycychc natural products isolated from the Australian plant Endiandra introrsa and exist naturally as a racemic mixture which is found to have very high antibacterial effect [73]. In 1980, Black and coworkers [74] proposed a hypothesis that these polycyclic systems are formed in nature by a series of electrocycUzation reactions. On the basis of this hypothesis, Nicolaou et al. [72c] in 1982 reported an excellent domino reduction/electrocyclization process for the synthesis of endiandric acid A 127 (Scheme 9.25). Selective hydrogenation using a Lindlar catalyst of diacetylenic diol 123 afforded the bicyclic diol 126. The reaction presumably proceeds via polyene 124, which then undergoes a spontaneous 8 [i-electrocyclization to give 125. It follows a second 6n-electrocyclization to afford bicyclic 126, which is further converted to endiandric acid A 127. 

Constit. of Endiandra introrsa. Rosettes (EtOH) and (CHCl3/petrol). Mp 163-165°. Racemic. 

Endiandra introrsa (Lauraceae) is a large tree growing in northern New South Wales and southern Queensland, Australia. Endiandric acid A (115) was obtained from leaves and leaf stems of this plant in a relatively high yield (0.45%) (2). The structure of this compound was determined as 2-(6 -phenyltetracyclo[5,4,2,0 , Oio,i2] trideca-4, 8 -dien-ir-yl)acetic acid by X-ray crystallographic analysis (2, 5). 

Bandaranayake W M, Banfield J E 1980 Endiandric acid, a novel carboxylic acid from Endiandra introrsa (Lauraceae) X-Ray structure determination. J Chem Soc Chem Commun 162-163... 

Bandaranayake W M, Banfield J E, Black D St C, Fallon G D, Gatehouse B M 1982 Constituents of Endiandra species. III. 4-[( ,E)-5 -Phenylpenta-2, 4 -dien-F-yl]tetracyclo-[5,4,0,0 , 0 ]-undec-lO-ene-8-carboxylic acid from Endiandra introrsa (Lauraceae). Aust J Chem 35 567-579... 

Finally, it is interesting to speculate that Nature may actually utilize aqueous Diels-Alder chemistry for the biosynthesis of the endiandric acids. These compounds are produced in the leaves of Endiandra introrsa (Lauraceae) - presumably in the vicinity of a largely aqueous cellular medium. The biosynthesis of endiandric acid A (1.10) proposed by Black s group [5] involves two sequential electrocyclization reactions (1.7 1.8- 1.9) followed by an intramolecular Diels-Alder reaction to give... 

The endiandric acids, e.g. (142), are an interesting series of natural products which were isolated recently from leaves of the Australian shrub Endiandra introrsa. They each have eight asymmetric centres, and occur in Nature in racemic rather than enantiomeric forms, which is a rather unusual observation for naturally occurring compounds. 

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