Indolizidine alkaloids monomorine

These have been much less popular, but some examples have been reported. These involve only alkenyltins containing one additional moiety on the G-carbon this substituent can be trimethylsilylmethyl (leading to functionalized allylsilanes [37] or divinyl ketones (Scheme 4-10) [38]) or trifluoromethyl [39]. The substituent can also be in the /3-position (E-geometry) examples have been reported by Parrain et al. [40] and Castano et al., the latter having used the coupling reaction of a jS-stannyl enone as the key step in the preparation of the indolizidine alkaloid ( )-monomorine here the coupling step is followed by an immediate in-situ reduction of the intermediate enone, the mechanism of which is unclear (Scheme 4-11) [41J. 

The indolizidine alkaloid (+ )-monomorine I (373), isolated from Pharaoh s ant Mono-morium pharaonis, is the first example of an indolizidine alkaloid found in the animal kingdom. One enantioselective total synthesis of 373 exploits an asymmetric cycloaddition of nitrone 370 to the chiral allylic ether 369, which is prepared from 349. The conversion of 349 to a tosylate followed by treatment with -propylmagnesium bromide in the presence of... 

Perhydropyrido[l,2-fr][l,2]oxazine 10 was applied in the total synthesis of (-)-monomorine I, an indolizidine alkaloid, to control the stereoselectivity (09S655). 

The concise enantioselective total synthesis of (+)-monomorine I, a 3,5-dialkyl-substituted indolizidine alkaloid, was completed by S. Blechert et al. using a sequential cross-metathesis double reductive cyclization strategy. The enedione substrate was prepared in two steps. The Stetter reaction between the masked equivalent of acrolein and butyl vinyl ketone was followed by a retro Diels-Alder reaction under flash vacuum pyrolysis (FVP) conditions. 

Hydroamination has been found to be useful in racemic synthesis of various natural products. Helquist and coworkers recently synthesized ( ) momomorine I using Ag-catalyzed hydroamination/cyclization of amino-diyne as the key step. Monomorine I is an indolizidine alkaloid isolated from ant Monomorium pharaoins. Beller and coworkers found hydroamination useful in the synthesis of amphetamines. It is worth mentioning that amphetamine is a class of compounds having several biological activities such as a stimulant to the central nervous system, an antiinflammatory agent, and inhibitors of enzymes. ... 

New asymmetric synthesis of the indolizidine alkaloids (-l-)-monomorine I (673) and (—)-indolizidine 195B (674) has been achieved from sulfinimine-derived chiral building blocks N-sulfinyl-5-amino-p-ketophosphonate (671) via 3-oxopyrrolidine phosphonates (672) (Scheme 169). ... 

Trifluorinated analogues of monomorin, an indolizidin-type alkaloid that is an ant pheromone,and of vincamine derivatives have been described (Figure 4.54). ... 

Disubstituted indolizidines, unlike many classes of amphibian alkaloids, are not unique to amphibians. 3,5-Disubstituted indolizidines such as monomorine I [(5Z,9Z)-195B] occur in ants of the genera Monomorium and Solenopsis (125,129,134). Some of the ant indolizidines are as follows (5Z,9Z)-3-n-butyl-5-methylindolizidine (monomorine I), (5Z,9Z)-3- -ethyl-5-methylindolizidine, (5Z,9Z)-3-hexyl-5-methylindolizidine, and (5 ,9Z)-3-butyl-5-(4-pentenyl)indolizidine. A series of 5-substituted indolizidines, the piclavines, were reported recently from a marine tunicate (Clavelina picta) (135). 

All the currently known indolizidine and quinolizidine alkaloids isolated from ants are illustrated in Fig. 6. (+ )-Monomorine I (427), the well-studied trail pheromone constituent of the Pharaoh ant Monomorium pharaonis), and the analogs 428-431 were described in the earlier volumes in this series. These five compounds are 3,5-disubstituted indolizidines bearing short saturated or mono-unsaturated hydrocarbon chains. The relative stereochemistry in monomorine VI (430) still remains unknown, while that of 431 was atypical for the class at the time of its isolation 380). The structural resemblance of fiiis group of alkaloids to the... 

The synthesis of indolizidine 195B (450) has in general been the fortuitous result of indifferent diastereoselectivity in routes to its diastereomer monomorine I (427). The racemic alkaloid accompanied ( )-monomorine I, and sometimes other diastereomers, in several post-1985 syntheses (393,397,399,400,402,403). Enantioselective syntheses of 450 published during the period 1985-1993, most of them also producing 427, were discussed in Volume 44 of this treatise (2), while post-1993 enantioselective syntheses leading to mixtures of 427 and 450 were detailed in Section V.A of this chapter (404,410,413,415,419). A conference paper describing the synthesis of (+ )-450 and the C-5 epimer (+ )-595 was also highlighted in Volume 44 this work has subsequently been published with full experimental details (468). 

Previous treatment of the indolizidine and quinohzidine alkaloid constituents of ant secretions may be found in Volume 55 of this series. An important review describing the defensive chemistry of ants, by Leclerq et al., deals with the occurrence, stmcture, function, and total synthesis of all the major groups of ant alkaloids, especially monomorine I vide infra. Section 6.1.2)... 

Toyooka and coworkers confirmed the constitution of the new toad alkaloid indolizidine 239Q (1716 cf Section 6.2.2) by total synthesis of the (-(-)-enantiomer (Scheme 231). " Their approach began with the same pyrrolidine (—)-1624 that Lesma and coworkers had used in their synthesis of (+)-monomorine I (1562) (cf. Scheme 205 Section 6.1.2). The ester... 

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