Isoiridomyrmecin

The application of this chemistry to the synthesis ofterpene natural products such as (—)-mitsugashiwalactone and (+)-isoiridomyrmecin [15] (Scheme 9.5) involved low-valent iron-catalyzed Alder-ene reactions in key steps in these synthesis. 

Propellane derivatives are available via intermolecular meta cycloaddition. Compounds 106 [81,82] and modhephene 107 [81] were obtained using this type of photocycloaddition (Sch. 21). Isoiridomyrmecin 108 [83] and decarboxyquadrone 109 [82] can be synthesized via the same photochemical key step. 

An analogous cycloaddition involving benzene and vinyl acetate (Scheme 20) also provides rapid access to simple bicyclo[3.3.0]octanes, which have many synthetic uses as illustrated in part by their value in a straightforward synthesis of isoiridomyrmecin (150). 

Wender and co-workers have continued their elegant use of the meta photocycloaddition of ethylenes to arenes as the key step in the synthesis of several naturally occurring compounds. The major product from irradiation of benzene and vinyl acetate is the 1-endo acetate of (36), and using this as the starting material, the total synthesis of the ant defensive secretion, isoiridomyrmecin (50), has been accomplished in seven further steps." There... 

S. Ito et al. utilized the aza-Claisen rearrangement of carboxamide enolates for the enantioselective total synthesis of (-)-isoiridomyrmecin, which is a constituent of Actinidia polygama and exhibits unique bioactivity. The rearrangement of the (S,S) stereoisomer was conducted under standard conditions, and the product was isolated as a single [R,R) stereoisomer in 77% yield. 

Eight- to sixteen-step syntheses of isoiridomyrmecin and verbenalol,763 iridomyr-mecin764 allodolicholactone (first synthesis), iridomyrmecin and its iso-epimer785 and sarracenin766 have been reported. 

Thus, Cid and Pombo-Villar have also described the synthesis of (-)-a-skytanthine (201) and (+)-epi-dihydrotecomanine (202) from the common intermediate 200 (195). Treatment of200with (4-toluenesulfonyl)hydrazide and in situ reduction with sodium cyanoborohydride afforded the piperi-done 203 in 44% yield. Debenzylation with Li-NH3 followed by reduction of the lactam 204 [which is formally an aza-analog of (+)-isoiridomyrmecin (205)] with UAIH4 gave 206, and iV-methylation under Eschweiler-Clarke conditions afforded (-)-a-skytanthine (201) (Scheme 12) (195). 

It should also be mentioned that substantial synthetic effort has been directed towards the formation of monoterpene lactone derivatives such as boschnialactone (217), iridomyrmecin (218), and isoiridomyrmecin (205)... 

Another application of the stereoselective tandem cyelization is the synthesis of isoiri-domyrmecin from an acyclic precursor97. Reductive cyelization of 4-bromo-5-methyl-l-trimethylsilyl-8-decen-l-yne gives a mixture of four bicyclic products in a ratio of 47 44 5 4. Conversion to the bicyclic ketone, an intermediate in the synthesis of isoiridomyrmecin, shows the potential utility of this approach in natural product synthesis. 

Cyclopentanes, Iridoids, Monoterpenoid Alkaloids. ( —)-Bromodihydro-umbellulone (5) ( —)-isoiridomyrmecin (6) ( + )-iridomyrmecin (7) at — 150 loganin penta-acetate Rionomethyl ether bromide the rubidium... 

Ozonolysis of 91, followed by reductive work-up with sodium borohydride, afforded directly the isoiridomyrmecin 92. 

The authors also showed the possibility, by employing suitable starting products, such as S-pulegone, to obtain iridomyrmecin, isoiridomyrmecin and teucriumlactone with the same Homer-Wadsworth-Emmons reaction. 

This abnormal insertion mode was applied in a total synthesis of the natural product ( )-isoiridomyrmecin 197 in seven steps starting from 2,3-butadienyl bromide (Scheme 57). ... 

The fruits of plants of the genus Actinidia cause abnormal excitement for animals of the cat genus, such as cats and lions. Matatabilaaone, obtained from mokutenryou, possesses the same effect [1]. It was foimd that matat-abilactone was a mixture, and that it contained dihydronepetalaaone, isodi-hydronepetalactone, iridomyrmecin, and isoiridomyrmecin 1—A. ... 

Plants of Actinidia polygama (Actinidiaceae) have an excitatory effect on cats and odier Felidae. This plant is also used in folk medicine in Japan. Several iridoid monoterpenes have been isolated [iridomyrmecin (1), isoiridomyrmecin (44), dihydronepetalactone (31), isodihydronepetalactone... 

Iridomyrmecin (1) and isoiridomyrmecin (44) are used by ants such as Iridomyrmex humilis, /. nitidis, and Doli-choderus scabridus as defensive compounds. These lactones also were found in Aphis polygama. Thus, the structures of the lacewing atb-actants correspond to the reduced forms of the defensive compounds of ants (Sakan et al., 1970). 

Hofferberth et al. reported diastereoselective synthesis of several ant-associated iridoids, namely, nepetalactol (85), dolichodial (86), dihydronepetalactone (87), and isoiridomyrmecin (88), from citronellal (89) using common laboratory reagents (Scheme 97.8) [115]. 

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