Allylic alcohols gives

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

Tandem transesterification and diastereoselective intramolecular 1,3-dipolar cycloaddition of a-methoxycarbonylnitrones with chiral allyl alcohols give polycyclic compounds in one step with high stereoselectivity (Scheme 8.14).76 Transition state Ain Scheme 8.14 is more favorable than B because B has severe steric interaction (allylic 1,3-strain).77... 

This method, specific for the epoxidation of allylic alcohols, gives good results if the reaction is carried out under strictly anhydrous conditions, otherwise the yield or the enantiomeric excess can decrease, sometimes dramatically. This can explain the small differences between the results obtained during the validation experiments and the published results. All the different reagents are commercially available they can be used as received but in case of low yield and/or enantiomeric excess they should be distilled and dried under an inert atmosphere. Table 5.1 gives some other examples of substrates which can be epoxidized using the procedure described above. 

Mdrour also explored the Heck reactions of indolyl triflates with allylic alcohols [139, 258]. For example, reaction of triflate 227 with allyl alcohol gives the rearranged allylic alcohol 228 [139],... 

Further studies on the 1,3-dipolar cycloadditions of these molecules (86) have been reported. Addition of allyl alcohol gives endo adducts (505) which are not isolated but spontaneously cyclize to tricyclic products (506). Similar tricyclic products were also obtained using A-allylbenzenesulfonamide, triethylammonium acrylate, and vinylpyridines as dipolarophiles. It has previously been shown that the pyridinium-3-olates with chloroketenes (RCC1=C=O) give 2-oxofuro [2,3-c] pyridine 507 (see p. 22). Further studies demonstrate that when bromoketenes (RCBr=C=O) are used as dipolarophiles, a mixture of 2-oxofuro[2,3-c]pyridines (507) and isomeric... 

Catalytic alcoholysis reactions between secondary silanes and allylic alcohols give allyloxyhydrosilane products, in which Si-H and C=C double bond functionalities are present [Eq. (61)]. 

A chiral zinc(II) complex derived from Et2Zn and diisopropyl (/ ,/ )-tartrate as a chiral auxiliary is applied to the asymmetric 1,3-dipolar cycloaddition of nitrile oxides to an achiral allylic alcohol, giving the corresponding (R)-2-isoxazolines with high enantioselectivity. Addition of a small amount of ethereal compounds such as DME and 1,4-dioxane is crucial for achieving the high asymmetric induction in a reproducible manner [71] (Eq. 8A.47). 

The reactions of tertiary allylic amines with vinylic halides are related closely to the allylic alcohol reactions since enamines are often major products. We have just begun work in this area and have few results to report yet. We have seen some significant differences in the products formed from tertiary allylic amines and from the related allylic alcohols. A typical example is the reaction of 2-bromopropene with N-allyl piperidine and piperdine where a 42% yield of a single enamine is obtained (6). The related reaction with allyl alcohol gives a mixture of regioisomeric enamines. 

Acetone, likewise isomeric with allyl alcohol, gives the same products as propyl aldehyde. As the quantity of carbon monoxide does not decrease in the presence of phosphorus, Hemp-tinne concludes that the following decomposition process occurs ... 

Ans. Allyl alcohol coordinates to titanium through the OH functionality. The rate-determining step is unimolecular (both hydroperoxide and substrate are coordinated to metal) for allyl alcohol but bimolecular (n-hexene does not coordinate) for n-hexene. The favorable entropy of activation for allyl alcohol gives a faster rate. 

Less regularly used reagents are tert-hu y hydroperoxide, tf/Y-butyllithium, ozone. dioxiranes, fluorine/water/acetonitrile, or A, A -diethylhydroxylamine. Alkenes carrying a donor substituent can also be epoxidized with pcracids. Fluorinated allylic alcohols give, under Sharpless conditions, epoxides in good yield and enantiosclcclivity. ... 

Epoxidation of acyclic allyl alcohols with peracid and Mo/TBHP displays an opposite stereospecificity to that for the V/TBHP system. Trimethylsilyl-substituted allylic alcohols give t/zreo-epoxyalcohols with MCPBA and erythro-alcohols with VO(acac)a-TBHP, with high stereoselectivity. In the stereospecific epoxidation of cis- and trans-allyl alcohols, formation of a transition state is assumed with the development of two H bonds between the hydrogen atom of the hydroxy group of the allyl alcohol and the oxygen of the peracid, and between the hydrogen of the peracid OH and the oxygen of the ether 10. An analysis of the diastereometric transition-state interactions for stereoselective epoxidation of acyclic allylic alcohols has been published. A conformational effect may be responsible for the unexpected cis major product in Eq. 2. 

The Sharpless asymmetric epoxidation of allyl alcohol gives the glycidol derivative 61 in 90% ee after in situ tosylation of 60 [63]. This process is working on a multiton-a-year scale (Arco Co., USA), facilitating the synthesis of a variety of /0-blockers. Asymmetric dihydroxylation of the allyl ether 63 catalyzed by a combined system of OSO4 and the cinchona alkaloid-based ligand 65 allows the commercial synthesis of the propranolol intermediate 64 in 91 % (Sepracor Co., USA) [64]. 

Oxidations. With microwave irradiation alcohols are oxidized by t-BuOOH, allylic alcohols give epoxides. 1,4-Dihydropyridines undergo aromatization, and sulfides are converted to sulfoxides. ... 

Oxidations. Alcohols undergo rapid oxidation when exposed to PhI(0Ac)2-Alj03 (with microwave irradiation) or PhlCOAc) with catalytic amount of TEMPO. The latter procedure is mild and selective. Primary alcohols can be converted to aldehydes without oxidizing secondary alcohols. (Z)-Allylic alcohols give (Z)-enals, 1,3-diols afford 3-ketols, and cholesterol is oxidized to the 5-en-one without migration of the double bond. Tertiary cyclopropanols fragment to release carboxylic acid and alkene moieties. ... 

The Sharpless epoxidation of allylic alcohols gives rise to moderate asymmetric amplification [5, 13]. One example is shown in Scheme 2. The epoxidation of chalcone by a hydroperoxide in the presence of a catalyst formed by the combination of (E)-BINOL and YfOi-Prfj, displays a similar asymmetric amplification... 

On the other hand, when an epoxy alcohol is the desired product, the reaction must be stopped before the fast isomer is consumed completely. Usually the reaction is stopped at 40 to 45% conversion. Although the direct epoxidation of racemic allylic alcohols gives the epoxides in good enantiomeric excesses, the epoxidation of the recovered unreacted allylic alcohols obtained by kinetic resolution provides epoxides of much high enantiopurity. 

It is interesting that isomeric allylic alcohols give a different proportion of olefins. If the Grignard reagent has no /8-hydrogen, the reaction leads to carbon-carbon bond formation 3... 

Thus, allyl alcohol gives a 60% yield of y-butyrolactone in acetonitrile , but only 2% in benzene . 

---