2-methyl-l-alkanol

Reactions of various terminal alkenes, some of them bearing heteroatom substituents, with Me3Al and a catalytic amount of Erker s chiral neomenthylindene-zirconocene dichloride provide, after oxidation with 02, 2-methyl-l-alkanols in high yields with up to 85% ee [76] (Scheme 8.37). 

Under unoptimized conditions, the reaction uniformly gives (/ )-2-methyl-l-alkanols with 65-75% ee. In the case of 1-octene, running the reaction at 0°C in 1,1-dichloro-ethane has improved the enantioselectivity from 72 to 81% ee. 

Having developed an efficient method for the synthesis of deoxypolypropionates, which was unprecedented, it was deeply understood that, only if ZACA products containing just one stereogenic carbon center can be readily and predictably purified, the ZACA-based asymmetric synthetic method would become much more widely applicable. The senior author recently became fully aware of the following strengths and weaknesses of the previously known lipase-catalyzed (S)-selective acetylation (i) Enantiomerically pure (R)-2-methyl-l-alkanols can be reliably obtained from their racemic mixtures, although the maximally attainable yield (or recovery) of (R)-alcohols of >98% ee is limited to 50% or, more specifically... 

Lithium aluminum hydride reduction furnishes racemic 2-alkyl-l-alkanols in good yields13. Thus, from alkylation of 1,3-diacylimidazolidinone 1 with benzyl bromide followed by reduction, a 73% yield of ra< -2-methyl-3-phenyl-l-propanol is obtained. When this sequence is carried out with (R,R)-1 as starting material, (S )-2-methyl-3-phenyl-l-propanol is obtained in 93% ee [a]D -10.2 (c = 1.1, C6H6) 13. 

R)-ALKYLOXIRANES OF HIGH ENANTIOMERIC PURITY FROM (S)-2-CHL0R0ALKAN0IC ACIDS YIA (S)-2-CHLORO-l-ALKANOLS (R)-METHYLOXIRANE (Oxirane, methyl- (R)-)... 

Some l-(2-furyl)-l-alkanols have also been resolved by hydrolase-catalyzed acylations (Scheme 4.20). Thus l-(2-furyl)-l-ethanol (46) is efficiently resolved by acylation with vinyl acetate catalyzed either by Lipozyme IM or PPL [77]. Resolution with a more complex acyl donor, ethoxyvinyl methyl fumarate, catalyzed by Lipase LIP (from Pseudomonas aeruginosa) has also been achieved [95]. The... 

After studying various nitrogen-containing compounds, we found that the zinc alkoxide of 2-methyl-l-(3-quinolyl)propan-l-ol 5 (Fig. 1) catalyzes the enantioselective formation of itself with the same configuration in the reaction between quinoline-3-carbaldehyde and z-P Zn to produce the product 5 in high ee (up to 94% ee) [58]. In addition, the 5-carbamoyl-3-pyridyl alkanol 6 (Fig. 1) can act as an efficient autocatalyst to catalyze its own production in a highly enantioselective manner (up to 86% ee) [59]. 

Then, we discovered that chiral 2-methyl-l-(5-pyrimidyl)propan-l-ol 8 serves as a highly enantioselective asymmetric autocatalyst for the addition of z-Pr2Zn to pyrimidine-5-carbaldehyde 7 (Scheme 4) [60]. In this compound, the formyl group is connected to the symmetric pyrimidine ring instead of the pyridine ring. When highly enantioenriched (S)-pyrimidyl alkanol 8 with 99% ee was employed as an asymmetric autocatalyst, (S)-8 with 95% ee composed of both the newly formed and the initially used 8 was obtained. The yield of the newly formed 8 was calculated to be 67% and the enantiomeric excess was 93% ee. 

Oracz, P. Liquid-vapor equihbrium and excess Gibbs energy of 2-propanol + 1-alkanols (C1-C5) or + 2-methyl-l-proptmol hit. DATA Ser., Sel. Data Mixtures, Ser. A 1989,17, 268-285... 

In the course of the continuing study [9a,b] on the enantioselective addition of dialkylzincs to aldehydes by using chiral amino alcohols such as diphenyl(l-methyl-2-pyrrolidinyl)methanol (45) (DPMPM) [48] A. A -dibutylnorephedrine 46 (DBNE) [49], and 2-pyrrolidinyl-l-phenyl-1-propanol (47) [50] as chiral catalysts, Soai et al. reacted pyridine-3-carbaldehyde (48) with dialkylzincs using (lS,2/ )-DBNE 46, which gave the corresponding chiral pyridyl alkanols 49 with 74-86% ee (Scheme 9.24) [51]. The reaction with aldehyde 48 proceeded more rapidly (1 h) than that with benzaldehyde (16 h), which indicates that the product (zinc alkoxide of pyridyl alkanol) also catalyzes the reaction to produce itself. This observation led them to search for an asymmetric autocatalysis by using chiral pyridyl alkanol. 

When 2-(ferf-bulylethynyl)pyrimidine-5-carbaldehyde 11, instead of the 2-methyl derivative 9, was subjected to reaction with z-P Zn in the presence of chiral leucine, highly enantioenriched pyrimidyl alkanol 12 with the absolute configuration corresponding to that of chiral leucine was also obtained. But it should be noted that the resulting alkanol 12 showed the opposite enan-tioselectivity to that of alkanol 10, i.e., L-leucine induces the production of (S)-alkanol 12 and D-leucine induces (R)-12, respectively [82]. The asymmetric amplification of 12 with an alkynyl substituent is more significant than that of the 2-methyl derivative 10 to increase to 96% ee (Scheme 11). 

The following dialkoxy tellurium tetrafluorides did not react with the corresponding alkanols (alkyl group given R1 = R2 = R3) methyl, ethyl, propyl, prop-2-en-l-yl, 2-phenylethyl, 2-acetylethyl, 2-(methoxycarbonyl)ethyl, 2-t-butoxyethyl, 2-phenoxy-ethyl, 2-iodoethyl, and 3-bromopropyl1. 

It transpired that amino acid derived 2-amino-l,l-diphcnyl-l-alkanols. for example. 2-amino-3-methyl-l,l-diphenylpentanol, could give asymmetric inductions of greater than 90% in borane reductions12. 

Letcher, T.M., Deenadayalu, N., Soko, B., Ramjugernath, D., Naicker, P.K., Ternary liquid-liquid equilibria for mixtures of l-methyl-3-octylimidazolium chloride plus an alkanol plus an alkane at 298.2 K and 1 bar, /. Chem. Eng. Data, 48,904-907,2003. 

The simultaneous addition of fluorine and an alkoxy group to give 1 can be carried out by the use of methyl hypofluorite433,708 or by fluorination in alkanols with cesium fluoroxysul-fate,435 438 709 perchloryl fluoride,437,460 4fi4 467 xenon difluoride,447 452 fluorine,470 1-fluoro-4-hydroxy-l,4-diazabicyclo[2.2.2]octane bis(tetrafluoroborate),707 or l-(chloromcthyl)-4-fluo-ro-l,4-diazabicyclo[2.2.2]octane bis(tetrafluoroborate) 431 705 710 Examples of these additions are the formation of 2,433 3,435 4,438 5,447 6447 and 7 431... 

Optically active 0-benzoylatrolactic acid and its methyl ester were reduced to 2-phenylpropionic acids with almost complete loss of optical activity [392]. On the other hand, Nonaka and coworkers [393] found that l-(2-pyridyl)alkanols were reduced to 2-alkylpyridines with configurational retention in acidic medium l-(4-pyridyl)alkanols gave racemic 4-alkylpyridines. The stereochemical course was discussed considering perpendicular adsorption of pyridylalkanol molecules on the cathode and the configurational stability of carbanion intermediates. 

Die Alkanolate konnen auch in l-Methyl-2-oxo-pyrrolidin umgesetzt werden. Zur Aufarbeitung wird das Ester-imid durch Zugabe von Wasser ausgefallt, abfiltriert, mit Wasser und Methanol gewaschen. 

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