Pheromone carpenter bee

An enantio-selective enzymatic hydrolysis of meso( )-2,5-diacetoxy-3-hexene gives (+)-( )-(25 ,5/ )-5-acetoxy-3-hexen-2-ol in 77% yield (92% ee).97 The monoacetate with its two allylic groups offers possibilities for stereo-controlled introduction of nucleophiles via Pd(0) catalysis. Synthesis of both enantiomers of the Carpenter bee pheromone based on this strategy is presented in Scheme 5.14.98... 

Additional examples where chloroacetates from acyclic dienes have been used include the synthesis of pentadienylamines [96], dienesulfones [97], c-methylenecyclopentenones [98], marine natural products [99], and the carpenter bee pheromone [82]. Some additional Synthetic applications of the chloroacetoxylation of cyclic dienes are given in Refs. [100-104]. Chloroacetoxylation was also used to prepare a number of starting materials for the intramolecular reactions discussed in this chapter. 

The diacetoxylation works well with a number of cyclic and acyclic conjugated dienes and has been applied to the synthesis of natural products . For example, the meso diacetate from 2,4-hexadiene was used for the enantiodivergent synthesis of the carpenter bee pheromone. ... 

The reagent was used to resolve 5-cyanopentane-2-ol (1), a precursor to the four possible isomeric lactones (3). One of the cis-enantiomers is the carpenter bee pheromone. ... 

Meso diacetates obtained from 1,4-diacetoxylation of conjugated dienes have been used for enzyme-catalyzed hydrolysis in enantioselective transformations [79-85]. In an application toward the carpenter bee pheromone (Scheme 11.18) [79], the meso-diacetate 54, obtained from stereoselective 1,4-diacetoxylation of (B,Z)-2,4-hexadiene, was enzymatically hydrolyzed to hydroxyacetate 55 with 92%... 

A further significant example is the stereospecific synthesis of (/ , 5 )-5-hydroxy-2-methylhexanoic acid lactone (the major component of the Carpenter bee pheromone) [5 c]. 

Efficient preparations are possible using Fe2(CO)9 according to two different methods (in THF, or in lower polarity solvents with ultrasound) to produce the ferralactone complexes in moderate to excellent yields. Removal of the metal to form 8-lactones has been successfully applied to total syntheses of parasorbic acid (23), the carpenter bee pheromone (24), and malyngolide (25). Epoxide-derived ferralactone complexes have provided key intermediates in syntheses of routiennocin, avermectin Bla, and (—)-valilactone. ... 

Reaction of 147 with the mixed cuprate of 3-methy 1-2-butene gives, in one step, (/ )-( — )-sulcatol (148) the enantiomer of an aggregation pheromone of a wood-boring ambrosia beetle [53]. Oxirane 147 has also been instrumental in the synthesis of (2S, 5/ )-2-methyl-5-hex-anolide (151), one of the antipodes of the sex pheromone of the carpenter bee [54] (Scheme 22) and the macrolide fungal metabolite (7 )-recifeiolide (155) [55] (Scheme 23). 

Alkyl 2-acyloxy-3-deoxy-D-eryt7zr o-hex-2-enopyranoside diesters (91) have been converted into chiral 5-hydroxy-2-methylhexanoic acid lactones which constituted the pheromone of the Carpenter bee. Treatment of (90) with boron trifluoride etherate gave (91), which on addition of methylenetriphenylphosphorane gave a most interesting transformation to (92). A further reaction sequence... 

Enantiomerically pure lactonic pheromones 607-611, of the carpenter bee, blacktailed deer, Japanese beetle, rove beetle, and Oriental hornet, respectively, have been synthesized from racemic cyano alcohols of type 612. The key to the success of the overall approach is the facile separation of diastereomeric carbamates derived from cyano alcohols of type 612 by automated multigram LC. The chosen approach also facilitates the assignment of absolute configurations to the lactone enantiomers and their precursors. In the case of 607, direct determination of enantiomeric purity and absolute configuration is also possible using the chiral solvating agent 2,2,2-trifluoro-l-(9-anthryl)ethanol [439]. 

Similarly, Ohveira et al. have reported the synthesis of all four possible dia-stereomers of a component of the pheromone blend of the carpenter bee Xylocopa hirutissima via alkylation of 4,4-dimethyl-2-oxazoline derivatives [61] (Scheme 23). In this case, the carboxylic acid, allowing the formation of the 5-lactone, is masked as an oxazoline. The reaction of the anion of 2-ethyl-4,4-dimethyl-2-oxazoline 120 with iodide 121 gave compound 122 in 92 % yield, which was hydrolyzed and cyclized in one-pot under acidic conditions to provide a mixture of stereoisomers 123 and 124. 

All four possible diastereomers of 2-methyl-5-hydroxyhexanoic acid lactone (628) have been synthesized by Pirkle and Adams (641) and await comparison with natural material to determine which is the pheromone of the carpenter bee. 

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