With neopentyl alcohol and

The use of ethanol as an achiral auxiliary gave the adduct 53 with 55% ee, while neopentyl alcohol and methanol gave 96 and 87% ee, respectively. These results suggested that the achiral alcohol might exert a steric effect on the stereoselectivity. However, the increase in enantioselectivity from 55% to about 96% when 2,2,2-trifluoroethanol (TFE) was used instead of ethanol indicates a possible significant inductive effect also. Good enantioselectivities were also obtained with carboxylic acids and phenols. 

Further optimization of this reaction was carried out with TFE as an achiral adduct, since reaction with TFE is much faster than that with neopentyl alcohol. We found that dimethyl- and diethylzinc were equally effective, and the chiral zinc reagent could be prepared by mixing the chiral modifier, the achiral alcohol and dialkylzinc reagent in any order without affecting the conversion and selectivity of the reaction. However, the ratio of chiral to achiral modifier does affect the efficiency of the reaction. Less than 1 equiv of the chiral modifier lowered the ee %. For example with 0.8 equiv of 46 the enantiomeric excess of 53 was only 58.8% but with 1 equiv of 46 it was increased to 95.6%. Reaction temperature has a little effect on the enantiomeric excess. Reactions with zinc alkoxide derived for 46 and TFE gave 53 with 99.2% ee at 0°C and 94.0% ee at 40°C. 

A. Neopentyl iodide. A 500-ml. two-necked round-bottomed flask is fitted with a reflux condenser to which is attached a calcium chloride drying tube. One hundred thirty-six grams (115 ml., 0.44 mole) of triphenyl phosphite, 35.2 g. (0.4 mole) of neopentyl alcohol, and 85 g. (37 ml., 0.60 mole) of methyl iodide (Note 1) are added to the flask, and a thermometer is inserted that is of sufficient length to extend into the liquid contents of the flask. The mixture is heated under gentle reflux... 

Phosphite diiodide converts alcohols to iodides. This reagent has been used much less often than the corresponding dibromides or dichlorides. Phosphite methiodides give better yields of iodides in the reaction with primary, secondary and tertiary alcohols and are simple to use. Neopentyl iodide is isolated in 70% yield from the reaction of triphenyl phosphite, neopentyl alcohol and methyl iodide (equation 25). This reaction is remarkable considering the severe steric bulk of the neopentyl group which often makes rearrangement become the major process. 

Rydon4 gives details of a procedure (A), which is the simplest and the best for use with sterically hindered alcohols (e.g., neopentyl alcohol) and another (B) which is preferable for sensitive alcohols. 

With the exception of neopentyl alcohol (mp 53°C), the amyl alcohols are clear, colorless Hquids under atmospheric conditions, with characteristic, slightly pungent and penetrating odors. They have relatively higher boiling poiats than ketonic or hydrocarbon counterparts and are considered iatermediate boiling solvents for coating systems (Table 1) (1—16). 

Amination. Amyl alcohols can react with ammonia or alkylamines to form primary, secondary, or tertiary-substituted amines. Eor example, 3-methyl-butylamine [107-85-7] is produced by reductive ammonolysis of 3-methyl-1-butanol over a Ni catalyst at 150°C (59). Some diisoamyl- and triisoamyl amines are also formed in this reaction. Good selectivities (88%) of neopentyl amine [5813-64-9] are similarly produced by reductive ammonolysis of neopentyl alcohol (60). 

Esters derived from the primary alcohols are the most stable and those derived from the tertiary alcohols are the least stable. The decomposition temperature is lower in polar solvents, eg, dimethyl sulfoxide (DMSO), with decomposition occurring at 20°C for esters derived from the tertiary alcohols (38). Esters of benzyl xanthic acid yield stilbenes on heating, and those from neopentyl alcohols thermally rearrange to the corresponding dithiol esters (39,40). The dialkyl xanthate esters catalytically rearrange to the dithiol esters with conventional Lewis acids or trifluoroacetic acid (41,42). The esters are also catalytically rearranged to the dithiolesters by pyridine Ai-oxide catalysts (43) ... 

These reactions are also quite sensitive to steric factors, as shown by the fact that if 1-butene reacts with di(j iAisoamyl)borane the initially formed product is 99% substituted in the 1-position (15) compared to 93% for unsubstituted borane. Similarly, the product obtained from hydroformylation of isobutylene is about 97% isoamyl alcohol and 3% neopentyl alcohol (17). Reaction of isobutylene with aluminum hydride yields only triisobutjlaluininum. 

Neopentyl alcohol has been made by lithium aluminum hydride reduction of trimethylacetic acid and by treating ferf-butyl-magnesium chloride with methyl formate. ... 

Primary, secondary, and tertiary alcohols can be converted to any of the four halides by treatment with the appropriate NaX, KX, or NH4X in polyhydrogen fluoride-pyridine solution." This method is even successful for neopentyl halides. Another reagent that converts neopentyl alcohol to neopentyl chloride, in 95% yield, is PPh3-CCl3CN." ... 

Iridium-catalyzed transfer hydrogenation of aldehyde 73 in the presence of 1,1-dimethylallene promotes tert-prenylation [64] to form the secondary neopentyl alcohol 74. In this process, isopropanol serves as the hydrogen donor, and the isolated iridium complex prepared from [Ir(cod)Cl]2, allyl acetate, m-nitrobenzoic acid, and (S)-SEGPHOS is used as catalyst. Complete levels of catalyst-directed diastereoselectivity are observed. Exposure of neopentyl alcohol 74 to acetic anhydride followed by ozonolysis provides p-acetoxy aldehyde 75. Reductive coupling of aldehyde 75 with allyl acetate under transfer hydrogenation conditions results in the formation of homoallylic alcohol 76. As the stereochemistry of this addition is irrelevant, an achiral iridium complex derived from [Ir(cod)Cl]2, allyl acetate, m-nitrobenzoic acid, and BIPHEP was employed as catalyst (Scheme 5.9). 

Pillai and Pines (84) found that neopentyl alcohol, mixed with 10% by weight of piperidine and passed over alumina prepared from aluminum isopropoxide, yielded 2-methyl-l-butene and 2-methyl-2-butene, in a maximum ratio of 3, and small amounts of 1,1-dimethylcyclo-propane. However, lert-pentyl alcohol yielded these two olefins in a maximum ratio of only 1.4, and none of the cyclopropane was produced (Table VI). Because of these facts a carbonium ion mechanism which is applicable to ferf-pentyl alcohol is not adequate to explain the rearrangement taking place during the dehydration of neopentyl alcohol,... 

The dehydration of neopentyl alcohol can best be explained by a concerted mechanism involving the removal of the proton from the y-carbon atom by the basic sites and of the hydroxyl group by the acid sites of the alumina, with migration of the methyl group ... 

High yields (76-81%) of alcohols are also obtained by adding solutions of acyl chlorides in anhydrous dioxane or diethyl carbitol to a suspension of sodium borohydride in dioxane and brief heating of the mixtures on the steam bath [751], by stirring solutions of acyl chlorides in ether for 2-4 hours at room temperature with aluminum oxide (activity I) impregnated with a 50% aqueous solution of sodium borohydride (Alox) (yields 80-90%) [1014], by refluxing acyl chlorides with ether solutions of sodium trimethoxyborohydride [99], or by treatment of acyl chlorides in dichloromethane solutions with tetrabutylammonium borohydride at —78° [771]. A 94% yield of neopentyl alcohol was achieved by the reaction of trimethylacetyl chloride with tert-butylmagnesium chloride [324]. 

Birch reduction of the norgetrel intermediate 5 oil owed by hydrolysis of the enol ether gives the enone oxidation of the alcohol at 17 leads to dione 7. Fermentation of that intermediate in the presence of the mold PeniciIlium raistricky serves to introduce a hydroxyl group at the 15 position W. Acetal formation with neopentyl glycol affords the protected ketone which consists of a mixture of the A and A isomers (2 ) hindrance at position 17 ensures selective reaction of the 3 ketone. The... 

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