Pulo’ upone

B. striata, its secondary metabolic pattern, consisting of a series of uncommon polypropionates, is almost identical to that of its prey [36,37], On the contrary, if the mollusc, under maintenance in an aquarium, feeds on Haminoea navicula, it discharges [5] in the form of a yellow secretion two Haminoea metabolites, the haminols (8,9), structurally related to navenone-A (I), which possess alarm pheromone properties [38] for H. navicula. Studies on a third Aglajidae mollusc [39, 40], Philinopsis speciosa, led to the characterization of a 2-alkyl-pyridine, pulo upone (10), as a minor constituent co-occurring with two polypropionates closely related to the metabolites from the pair P. depicta-B. striata. 

Camphor sultam derivatives have proved to be effective chiral auxiliaries in many different types of asymmetric reactions. As shown in Scheme 5-44, chiral camphor sulfam can be applied in the synthesis of (—)-pulo upone precursor 151 using an intramolecular Diels-Alder reaction. A Wittig reaction of 148 with 147 connects the chiral auxiliary to the substrate, and subsequent intramolecular Diels-Alder reaction via transition state 150 affords product 151. Compound 151 already has the stereochemistry of (—)-pulo upone 153.72... 

The sex attractant of the sea slug Navanax inermis contains pyridine bases, one of which is the 3-pyridyltetraenone (140) (H.L. Sleeper and W. Fenical, J.Amer.chem.Soc., 1977, 99, 2367). Another structure, perhaps of vegetable origin, is pulo upone (153) which has been isolated as a trace constituent of the Hawaiian mollusc Philinopsis speciosa (S.J. Coval et al., Tetrahedron Letters, 1985, 26, 5359). 

Of these three highly diastereoselective methods for accomplishing asymmetric IMDA reactions, the a-hydroxy ketone protocol" [trienes (154) and (155)] is the least convenient owing to the greater difficulty of triene preparation, the moderate reactivity of the trienes, and the destructive removal of the auxiliary. Consequently, the auxiliary systems developed by Evans and Oppolzer are more likely to find application in natural products synthesis. Indeed, Oppolzer has recently applied the IV-acyl sultam methodology to the asymmetric total synthesis of (-)-pulo upone (Figure 43). °... 

Pulo upone (110) was isolated from the Hawaiin mollusk Philinopsis speciosa, and its structure was determined using HRMS, UV, and one- and two-dimensional NMR [312]. Several syntheses of 110 have been reported which utilize a Diels-Alder reaction for formation... 

Pelttari, E., Matikainen, J., and Flo, H. (2002) Antimicrobial activity of the marine alkaloids haminol and pulo upone and related compounds, Z, Naturforsch., 57c, 548—552,... 

Oppolzer, W., Dupuis, D., Poli, G., Raynham, T.M., and Bemardinelli, G. (1988) Enantioselective synthesis and absolute configuration of (—)-pulo upone by asymmetric intramolecular Diels—Alder reaction. Tetrahedron Lett., 29, 5885-5888. 

The use of amides and imides as chiral auxiliaries in [4 + 2]-cycloadditions has been the subject of numerous investigations. Oppolzer reported the use of camphorsultam 112 in asymmetric Diels-Alder reactions [26, 67. 68], The camphor sultam is readily available in both enantiomeric forms from cam-phorsulfonyl chloride. Acrylate 113 was found to react with cyclopentadiene in the presence of EtAlCl2 to give 115 with high selectivity (endo/exo = 99.5 0.5, dr = 97.5 2.5, Equation 10) [67]. Oppolzer also reported that triene 116 participated in an intramolecular Diels-Alder cycloaddition reaction to afford endo product 117 in 71 % yield and 96.5 3.5 dr (Scheme 17.19) [69]. This bicyclic product was subsequently converted into the pyridine alkaloid (-)-pulo upone (118). 

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