2-Methyl-1-propanol synthesis

Fig. 3. Synthesis of fluoxetine (31). 3-ChIoro-I-phenyl-I-propanol reacts with sodium iodide to afford the corresponding iodo derivative, followed by reaction with methylamine, to form 3-(methyl amin o)-1-phenyl-1-propan 0I. To the alkoxide of this product, generated using sodium hydride, 4-fluorobenzotrifluoride is added to yield after work-up the free base of the racemic fluoxetine (31), thence transformed to the hydrochloride (51)...

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Fig. 3. Stepwise synthesis of rifaximin (from De Angelis [39]). The reaction of rifamycin S (I) with pyridine perbro-mide (II) in 2-propanol/chloroform (70/30) mixture at 0°C gives 3-bromorifamycin S (III), which is then condensed with 2-amino-4-methyl-pyridine (IV) at 10°C. The o-quinonimic compound (V) is then obtained. This compound is finally reduced with ascorbic acid to rifaximin. 

Various nucleophiles other than methanol can be introduced onto the carbonyl carbon. Anodic oxidation of acylsilanes in the presence of allyl alcohol, 2-methyl-2-propanol, water, and methyl /V-methylcarbamate in dichlorometh-ane affords the corresponding esters, carboxylic acid, and amide derivatives (Scheme 24) [16]. Therefore, anodic oxidation provides a useful method for the synthesis of esters and amides under neutral conditions. 

D-Ribonolactone is a convenient source of chiral cyclopentenones, acyclic structures, and oxacyclic systems, useful intermediates for the synthesis of biologically important molecules. Cyclopentenones derived from ribono-lactone have been employed for the synthesis of prostanoids and carbocyclic nucleosides. The cyclopentenone 280 was synthesized (265) from 2,3-0-cyclohexylidene-D-ribono-1,4-lactone (16b) by a threestep synthesis that involves successive periodate oxidation, glycosylation of the lactol with 2-propanol to give 279, and treatment of 279 with lithium dimethyl methyl-phosphonate. The enantiomer of 280 was prepared from D-mannose by converting it to the corresponding lactone, which was selectively protected at HO-2, HO-3 by acetalization. Likewise, the isopropylidene derivative 282 was obtained (266) via the intermediate unsaturated lactone 281, prepared from 16a. Reduction of 281 with di-tert-butoxy lithium aluminum hydride, followed by mesylation, gave 282. 

Synthesis of hindered morpholinones or piperazinones from ketones (such as acetone) and 2-amino-2-methyl-l-propanol or 1,2-diaminopropanes. 

Trimethylarsonioribosides have also been synthesized (Fig. 5). Compound 33 was first isolated from a brown alga and was subsequently prepared by addition of methyl iodide to the arsine obtained on reduction of the natural product 17 with borohydride solution (64). Compound 33 has also been prepared by using 2,3-dimercapto-propanol as the reductant, and this procedure was similarly used for the synthesis of compounds 34 to 37 from the respective dimethylated compounds (65). 

We found a solution with new, doubly promoted platinum catalysts on silica and reported their scope and limitations for the synthesis of various aniline derivatives (ref. 5). In the following communication we describe the development of the most effective catalyst using as model reaction the N-alkylation of 2-methyl-6-ethylaniline with methoxy-2-propanol. 

If milder acidic conditions are required, acetic acid in refluxing 2-propanol is effective and these conditions leave methyl esters intact as shown in Scheme 6.26, which is taken from a synthesis of the indole alkaloid Vincamine,71... 

Suppose, for example, that we are asked to prepare (CH3)2CHCH20H (2-methyl-l-propanol) from an alkyl halide and any required reagents. To accomplish this synthesis, we must fill in the boxes for the starting material and reagent in the accompanying equation. 

Columbia. The preparation of the reagent from 2-amino-2-methyl-l-propanol and formic acid is described in a note to a procedure for the synthesis of o-anisaldehyde ... 

A new strategy for the synthesis of heterocyclic a-amino acids utilizing the Hantzsch dihydropyridine synthesis was developed in the laboratory of A. Dondoni." ° The enantiopure oxazolidinyl keto ester was condensed with benzaldehyde and fert-butyl amino crotonate in the presence of molecular sieves in 2-methyl-2-propanol to give a 85% yield of diastereomeric 1,4-dihydropyridines. The acetonide protecting group was removed and the resulting amino alcohol was oxidized to the target 2-pyridyl a-alanine derivative. 

An acceptable method is to oxidize methyl benzyl carbinol (l-phenyl-2-propanol) to phenylacetone (methyl benzyl ketone) with chrome oxide (CrO3) in pyridine solvent. The problem with this is that methyl benzyl carbinol is not commercially available, and so must be made from benzyl chloride grignard reagent and acetaldehyde. This grignard works well, although there can be a problem getting unreacted benzyl chloride out of the product. Their boiling points are very close, so distillation does not separate them completely. But the real question is Why make the synthesis of phenylacetone a two-step process when it can be done with one reaction ... 

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