Alcohols of alkenes

In the absence of alkene, alcohols lose hydrogen to the Ti—H202 complex to form water and ketone or aldehyde as shown in Fig. 6—IO47,49... 

Using dicyclohexyl-18-crown-6 it is possible to dissolve potassium hydroxide in benzene at a concentration which exceeds 0.15 mol dm-3 (Pedersen, 1967). The free OH- has been shown to be an excellent reagent for ester hydrolysis under such conditions. The related solubilization of potassium permanganate in benzene, to yield purple benzene , enables oxidations to be performed in this solvent (Hiraoka, 1982). Thus, it is possible to oxidize a range of alkenes, alcohols, aldehydes, and alkylbenzenes under mild conditions using this solubilized reagent. For example, purple benzene will oxidize many alkenes or alcohols virtually instantaneously at room temperature to yield the corresponding carboxylic acids in near-quantitative yields (Sam Simmons, 1972). 

The first general application of this procedure was to tiie synthesis of tetrahydrofiirfuryl alcohols, the precursor mercurials of which resulted from an intramolecular reaction of alkenic alcohols (Scheme 31) 61.62 3q mercurials and alcohols were formed as diastereomeric mixtures, the latter in moderate yields (Table 2). 

The preparation of alkenic alcohols based on rDA processes has found application in the synthesis of natural products. Matsutake alcohol (14a (-)-( )-l-octen-3-ol), an important flavor component of mushrooms, can be prepared in high enantiomeric purity by a method that includes rDA cleavage as a key step. Asymmetric DA addition gave enantiomerically pure adducts that were modified dia-... 

The applications of ruthenium tetroxide range from the common types of oxidations, such as those of alkenes, alcohols, and aldehydes to carboxylic acids [701, 774, 939, 940] of secondary alcohols to ketones [701, 940, 941] of aldehydes to acids (in poor yields) [940] of aromatic hydrocarbons to quinones [942, 943] or acids [701, 774, 941] and of sulfides to sulfoxides and sulfones [942], to specific ones like the oxidation of acetylenes to vicinal dicarbonyl compounds [9JS], of ethers to esters [940], of cyclic imines to lactams [944], and of lactams to imides [940]. 

Alcohols can be obtained from many other classes of compounds such as alkyl halides, amines, al-kenes, epoxides and carbonyl compounds. The addition of nucleophiles to carbonyl compounds is a versatile and convenient methc for the the preparation of alcohols. Regioselective oxirane ring opening of epoxides by nucleophiles is another important route for the synthesis of alcohols. However, stereospe-cific oxirane ring formation is prerequisite to the use of epoxides in organic synthesis. The chemistry of epoxides has been extensively studied in this decade and the development of the diastereoselective oxidations of alkenic alcohols makes epoxy alcohols with definite configurations readily available. Recently developed asymmetric epoxidation of prochiral allylic alcohols allows the enantioselective synthesis of 2,3-epoxy alcohols. 

Primary aliphatic amines react with nitrous acid through a reaction called diawtization to yield highly unstable aliphatic diazonium salts. Even at low temperatures, aliphatic diazonium salts decompose spontaneously by losing nitrogen to form carbocations. The carbocations go on to produce mixtures of alkenes, alcohols, and alkyl halides by removal of a proton, reaction with H2O, and reaction with X ... 

The reaction tolerates a wide range of functional substituents and allows use of alkenes, alcohols, amines, esters, halogens, and nitriles. Reactions of 1,6-octadiynes with such monoynes results in ortho- and mefia-substituted derivatives. Regioselectivity of the reaction is controlled by the choice of the ligand. Thus, the interaction of diyne 2.10 and monoyne 2.11 in the presence of dppe [l,2-bis(diphenylphosphino)ethane] yields mainly the meta-isomer 2.12 (selectivity 88%), whereas in the presence of dppf [1,1 -bis(diphenylphosphino)ferrocene] the yield of ortho-isomerlA3 reaches 82% [39] (Scheme 2.5). 

Ruthenium-catalyzed Oxidation of Alkenes, Alcohols, Amines, Amides, P-Lactams, Phenols, and Hydrocarbons... 

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