Trail pheromones synthesis

Mori reported an improved synthesis of (3S,4P,6 ,10Z)-faranal (37), the trail pheromone of the Pharaoh s ant (Monomorium pharaonis) [84]. As summarized in Scheme 55, the key-reaction was the coupling of iododiene A with iodide E. The geometrically pure A was prepared by the zirconocene-mediated carbo-alumination reaction, and E was prepared from B by the asymmetric cleavage of its epoxy ring to give C (77% ee), which could be purified via its crystalline 3,5-dinitrobenzoate D. 

A trail pheromone of the Pharaoh ant was identified as 3-butyl-5-methylindolizidine of the stereochemistry given in (219) (75JHC289). Slaframine (220) is a metabolite isolated from Rhizoctonia leguminicola responsible for producing excessive salivation in cattle. A stereoselective synthesis was reported (73JOC3848). Swainsonine (221), a potent inhibitor of a-mannosidase, has been isolated from Swainsona caneszens. The stereochemistry was derived from the NMR spectrum (79AJC2257). 

The seco-phenanthroindolizidine alkaloid septicine has been synthesized by a nitrone route. A cycloaddition of 1-pyrroline 1-oxide with 2,3-bis-(3,4-dimethoxyphenyl)butadiene gives two stereoisomeric isoxazolidines, one of which is converted into ( ) septicine.10 ( )-Tylophorine and 5-coniceine have been prepared by a new route that makes use of an intramolecular imino-Diels-Alder reaction.11 A stereoselective synthesis of 3,5-dialkyl-indolizidines has been applied to the synthesis of a stereoisomer of the trail pheromone of the Pharaoh ant and to a stereoisomer of gephyrotoxin 223.12 A stereoselective total synthesis of ( )-perhydrogephyrotoxin (21)13 and a simple synthesis of ( )-gephyran14 have been reported. 

Explain the stereochemical control in this synthesis of a fused bicyclic saturated heterocycle—the trail pheromone of an ant. 

Anodic oxidation of amides and carbamates on the other hand are far more useful than those of amines. Scheme 46 shows the synthesis of a pharaoh ant trail pheromone in which the anodic oxidation of 2-pyrrolidone is an important step [270]. 

The conversion of prochiral centres in cyclic intermediates into fully blown chiral centres is a profitable way to transmit stereochemical information. The ant trail pheromone monomorine 42 when re-drawn so that we can see all three hydrogen atoms on the same surface of the molecule 42a, is an ideal candidate for synthesis by reductive animation. One of the three centres must be made asymetrically and then the other two set up by reduction of imines formed from that amine and two ketones as in 43. 

The same methodology is applied in the enantioselective synthesis of iodo ether 23, a key precursor of ( + )-faranal (24) (a trail pheromone of the Pharaoh s ant)969. 

A high degree of chiral transmission is observed in the synthesis of iodo acetal 19, a key intermediate in the total synthesis of ( + )-faranal (a trail pheromone of the Pharaoh s ant). The [2,3] Wittig process ot 16 followed by cis hydrogenation gives oxy-Cope substrate 17 with 100% E and Z and >99% threo. The oxy-Cope process of 17 affords en7//ro-aldehyde 18 as a single product with 91 % ee966. 

From the above survey of results the synthetic potential of the oxazinolactam intermediate 46 in hand, we envisaged to synthesize monomorine I (62) which constitutes of an extension of the methodology based on intramolecular nitroso Diels-Alder cycloaddition. The relative stereochemistry of this substance, isolated as one of the trail pheromones from Pharaoh ants (Monomorium pharaonis L.) (ref. 19), has been determined its relative stereochemistry by nonstereoselective synthesis (ref. 20). More recently, a stereospecific synthesis of racemic 62 (ref. 21) and a chiral synthesis of the (-)-enantiomer of natural 62 (ref. 22) were reported. 

GC-MS. For example, branched-chain primary alcohols have been oxidised to the corresponding acids and methylated for analysis, since the mass spectra of methyl esters are well documented [424,426], Others prepared pyrrolidides, after oxidation to the acids, as these give spectra which are more readily interpreted [46], Similarly, secondary alcohols have been oxidised to ketones as an aid to identification [113], Double bonds in alkyl chains of alcohols have been located by MS after the preparation of suitable chemical adducts, similar to those described for fatty acids in Chapter 7. Oxidation to diols and conversion to the TMS ethers is one method [638], but synthesis of dimethyl disulfide adducts from alcohol acetates is a one-step reaction (see Chapter 4) and is now preferred [143,540], On the other hand, it may be too much to expect that a single method will provide all the information desired on a given sample it required partial hydrogenation, coupled with GC-MS and GC/Fourier-transform IR (to identify frans-double bonds), to determine the structure of a trienoic insect trail pheromone [1006],... 

Maruoka and coworkers [65] also reported the total synthesis of (+) mono-morine (127) using a phase-transfer-catalyzed conjugate addition of glycine ester 128 to Michael acceptor 129 as an early key step in the synthesis sequence. Monomorine (127) is a bicyclic amine, known to be the trail pheromone of Monomorium pharanois [66]. The conjugate addition product 131 was subjected to an intramolecular reductive amination and acetal hydrolysis in one pot reaction with Hantzsch ester 132 and trifluoroacetic acid in aqueous... 

Methyl-3-heptanone (386a, Scheme 68), the alarm pheromone of the Texas leaf-cutting ant (Atta texana) was synthesized by Riley et al 173, 174) and required resolution of the intermediate, racemic 2-methyl-4-pentenoic acid (384). A convenient synthesis of methyl 4-methylpyrrole-2-carboxylate (392), the trail pheromone of A. texana, has been reported by Sonnet (775) (Scheme 69). Formylation of ester (390) with CUCHOMe and AICI3 gave predominantly the desired 4-formyl derivative (391). 

The synthesis of faranal, the trail pheromone of the common ant Monomorium pharaonis, was recently reported by Minnaard, Feringa, and coworkers [4]. Hence, CM of 5 with ethyl thioacrylate furnished the unsaturated thioester 6 in good yield along with 5% of the homodimer of 5 (Scheme 10.2). The second stereocenter was installed by an enantioselective conjugate addition, which led to 7 in both high yield and high selectivity. 

The Barton-Zard pyrrole synthesis has now been extensively applied to synthesis of naniral and unnaniral products containing pyrrole units Methyl 4-methylpyrrole-3-carboxylate is the trail-maker pheromone of the Texas leaf-aitting ant Arm lexaiia It is readily prepared by the Barton Zard method in 60% yield fEq 10 33 ... 

Recent trend in the synthesis of olefinic pheromones is the use of transition metal-catalyzed cross coupling reaction for carbon-carbon bond formation. Scheme 8 summarizes a synthesis of the termite trail marker pheromone, (3Z,6Z)-3,6-dodecadien- l-ol (2) by Oehlschlager [19]. The key-step is the palladium-catalyzed cross-coupling of allylic chloride A and alkenylalane B. 

---