1.3- Diols ketones

Compound types Aromatics Olefins Alcohols Nitriles Acids CHC12 CC13 CH2C1 NO, Diols Ketones Ethers Aldehydes N(Me), Esters Epoxides Nitromethane Nitrogroups Pyridine Dioxane Aromatic bases... 

Frontalin (18), the pheromone of the western pine beetle, is an acetal (atom has two single bonds to oxygen). Disconnection reveals diol ketone (19). 

Candidate compounds for sex pheromones have been isolated from cervico-vaginal mucus of domestic cows. Several diols, ketones, and amines were identified in fractions that released sexual responses in bulls, such as sniffing and licking the sample, fiehmen, penile contraction, and preputial secretion (Klemm etal, 1987). 

The first observation of the c/x-dihydroxylation reaction with RuO was made by Sharpless et al. in 1976, who noted that E and Z-cyclododecene were oxidised by stoich. RuO /EtOAc/-78 C to the threo and erythro diols [299]. Later RuCyaq. Na(IO )/EtOAc-CH3CN/0 C was used and reaction conditions optimised for many alkenes [300] a useful paper with good practical examples discusses the scope and limitations of the procedure (Table 3.2) [301]. Later oxidations were done with stoich. RuOyaq. acetone/-70 C [302] the same reagent converted A, and A steroids to cw-diols, ketones or acids [303], while RuO /aq. Na(10 )/acetone gave diones and acids [304]. 

Paraffin followed by candelilla wax and microcrystalline waxes, and eventually by beeswax, are considered as the most effective moisture barriers derived from edible waxes (Morillon et al. 2002). There is no satisfactory chemical definition for the term wax which is used for a variety of products of mineral, botanical and animal origin that contain various kinds of fatty materials (Table 23.4). The term resins or lacs can also be used for plant or insect secretions that take place along resins ducts, often in response to injury or infection, and result in more acidic substances (Hernandez 1994). However, all waxes tend to contain wax esters as major components, that is, esters of long-chain fatty alcohols with long chain fatty acids. Depending on their source, they may additionally include hydrocarbons, sterol esters, aliphatic aldehydes, primary and secondary alcohols, diols, ketones, triacylglycerols, and so on. 

Dioxolan 2-(Dichlor-methyl)-2-phenyl- E14a/1, 194 (Diol + Keton), 295 (Oxiran + Keton)... 

Benzodloxol 2,2-Diisopropyl-E14a/1. 173 (Diol + Keton) Benzoesaure -hexylester E5, 675 (OH - OR)... 

The routes leading from lactone A have the advantage of a chiral source of starting materials. With the two chiral centers at C24 and C25 set, the problem reduces down to elaborating the B ring with the appropriate substituents. An early solution was provided in an unusual cyclization of the B ring via an intramolecular Michael addition to the unsaturated aldehyde formed from a nitrile oxide 1,3-dipolar cycloaddition to the allyl methyl ketal of lactone A [76]. This clever use of relative stereocontrol provided by the highly constrained and predictable transition states of both key reactions unfortunately resulted in a low yield. A more conventional approach conceptualized the addition of a sulfoxide [77] to 2 to yield a masked diol-ketone precursor which cyclizes under acidic catalysis. Elimination of the sulfoxide permitted the introduction of the hydroxy substituent at C19 of the spiroketal. 

AUene Hydrobora-ting agent Reaction time (h) Residual aUene (%) Homo-allylic alcohol (%) Diol (%) Ketone (%)... 

Jeger s ketal (394), named after its discoverer, but also called Amberketal, Ambrake-tal, and Ketamber, is another material with a powerful ambergris odor. It is prepared from manool (395), extracted from the New Zealand tree Dacrydium biforme, by permanganate oxidation to the ketone (396) followed by osmylation of the double bond and spontaneous formation of the ketal from the resultant diol-ketone. It has also been synthesized from larixol (397), which is readily available from the European larch, Larix decidua 449). 

Alcohols, diols, ketones, esters, or chain cleavage/crosslinking... 

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