Andrena haemorrhoa

The reduction of nitro ketones with baker s yeast is a good method for the preparation of chiral nitro alcohols.89 The reduction of 5-nitro-2-pentanone with baker s yeast gives the corresponding (5)-alcohol, which is an important chiral building block. Various chiral natural products are prepared from it. In Scheme 7.16, the synthesis of the pheromone of Andrena haemorrhoa is described, where the acylation of the chiral nitro alcohol followed by radical denitration is involved as key steps.89a... 

Two important spiroketals, such as l,7-dioxaspiro[5.6]undecane (29a), the major component of the olive fruit fly (Dacus oleae) sex pheromone (Baker et ah, 1980 Fanelli et ah, 1983), and ( )-2-methyl-l,7-dioxaspiro[5.6]dodecane (29b), a component of pheromone of Andrena haemorrhoa (Bergstroem et al., 1981 Katsurada and Mori, 1984), have been prepared in a cascade process from polyfunctionalized nitroalkanes (26) (Ballini and Petrini, 1992). 

Bergstroem, G., Erancke, W., Reith, W., and Tengoe, J. 1981. Pheromone bonqnet of the man-dibnlar glands in Andrena haemorrhoa E. (Hym., Apoidea). Zeitschrift fuer Naturforschung, C Journal of Biosciences, 36C(ll-12) 928-32. 

Katsurada, M. and Mori, K. 1984. Pheromone synthesis. LXIV. Synthesis of the enantiomers of 2-methyl-l,7-dioxaspiro[5.6]dodecane, a component of the volatile secretion from the mandibular glands of Andrena haemorrhoa F. Liebig Annals of Chemistry, 1 157-61. 

Nitro compounds are also able to be reduced by stannanes under free-radical conditions. For example, Kitayama described the reduction of the nitro moiety in 74 by the action of BubSuH during his preparation of pheromones for Bactrocera Nigrotibialis, Andrem Wilkella and Andrena Haemorrhoa (equation 47). Petrini and coworkers reported the selective reduction of the nitro group in a series of ft), ft)-dichloro-ft)-alkanoates (75) it is interesting to note that the chlorine atoms remain intact during the reaction with Bu3SnH (equation 48). Witczak and coworkers described the reduction of substrate (76)... 

The volatile component of the mandibular secretion of Andrena haemorrhoa F. contains 2,7-dimethyl-l,6-dioxaspiro[4.6]undecane. All four thermodynamically stable stereoisomers of the Spiro acetal pheromone have been prepared using the two enantiomers of ethyl lactate (which supplies the 2-methyl substituent via butyrolactone 51) and the two enantiomers of 3-hydroxybutanoate (which supplies the 7-methyl via iodide 52). Scheme 8 shows the synthesis of the (2S, 5S, 7/ )-isomer 55. The overall yield in the sequence is 9%, and the purity of the final product is 97% [18]. 

Ethyl-2-methyl-l,6-dioxaspiro[4.5]decane is a pheromone produced by two varieties of bees, Parvespula vulgaris L. and Andrena haemorrhoa F. The 27 , 57 , 77 -isomer (188) has been synthesized using 147, ultimately derived from ethyl L-lactate, to supply the chiral stereocenter at C-2 (Scheme 26) [19]. The second chiral intermediate 185 is derived from (5)-( — )-malic acid. 

Andrena haemorrhoa [104], and (11) the pheromone component of the swift moth Hepi-alus hecta [105]. 

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