Propyl compounds

Deghenghi et al studied the reductive alkylation of 16-dehydropregneno-lone acetate in ammonia-tetrahydrofuran using excess lithium and alkyl iodides. Alkylation with methyl iodide followed by reacetylation of the 3-hydroxyl group affords 17a-methylpregnenolone acetate in 20% yield after purification by column chromatography. Ethyl iodide affords the 17a-ethyl analog in 40% yield, but n-propyl iodide affords the 17a-propyl compound in only a 12 % yield. 

For some tertiary substrates, the rate of SnI reactions is greatly increased by the relief of B strain in the formation of the carbocation (see p. 366). Except where B strain is involved, P branching has little effect on the SnI mechanism, except that carbocations with P branching undergo rearrangements readily. Of course, isobutyl and neopentyl are primary substrates, and for this reason they react very slowly by the SnI mechanism, but not more slowly than the corresponding ethyl or propyl compounds. 

FIGURE 6.3. Examples of bioactive pentafluoro- and hexafluoro-w-propyl compounds... 

Fluorine NMR data for a number of heptafluoro-n-propyl compounds are given in Scheme 6.19. Little vicinal three-bond F—F coupling is observed for most n-C3F7 compounds (alkyne exception below) rather more prominent is the four-bond coupling (probably significantly through space). 

We initially prepared racemic analogs to readily probe effects of differing C3, C3 substitution. The synthesis of 90-97 (Schemes 7.22 and 7.23) commenced with racemic bisallyl 61 (see Scheme 7.14). Subsequent hydrogenation yielded the bis-n-propyl compound, and here the lack of functionalization of the C7,C7,-groups allowed facile C5,C5 -hydroxylation with Kita s reagent [40] to provide 56, as we discovered during our work on the model system (Scheme 7.12). 

The association of aluminum alkyls provides a good opportunity to illustrate the principles discussed in Chapter 6 in regard to properties of liquids. Measurements of the molecular weights in benzene solutions indicate that the methyl, ethyl, and n-propyl compounds are completely dimerized. However, the heat of dissociation of (A1R3)2 dimers varies with nature of the alkyl group as shown by the following heats of dissociation ... 

An interesting contrast is shown in the stabilities of the aziridines derived from the isomeric A-/erf-butyl 2-methylpropylideneimine and A-iso-propyl 2,2-dimethyl-propylidineimine. Solvolysis of the A-terr-butyl derivative occurs readily under the basic conditions, whereas the aziridine derived from the A-wo-propyl compound is more stable and can be isolated in 75% yield. 

A related ligand, MPL (3-methoxypropanol), was combined with Al(f-Bu)3 and Al(Me)3 [28]. The resulting Bll compound was similar to those formed by MEL, with a dative interaction in the methyl compound but not the f-butyl one. However, the dative bond is much longer (2.39 A vs. 2.27 A) for the propyl compound. Another related ligand is MlP(l-methoxy-2-propanol), which was combined with Ga(Me)3 [33]. This complex is nearly identical to that formed by MEL with Ga(Me)3. 

Paris, M., F. Boucher and L. Cosson. Importance of propyl compounds in cannabis originating in South Africa. Plant Med Phytother 1975 9 136. Payne, R. J. and S. N. Brand. The toxicity of intravenously used marihuana. 

Under identical conditions the acetylated glucosides were formed more easily than the acetylated glucuronides, albeit both derivatives of hydroxymethyl me-thylnitrosamine XVIII (R- =CH3 R2=H) were obtained only in traces, whereas the corresponding n-propyl compounds are isolable in yields up to 30%. 

Hydrogenation of the 1-propargyl and 1-allyl derivatives of 63 (R = H) over Pd/CaC03 or Pd/C gave the 1-propyl compound,103 273 whereas 2-propargyloxy-4-oxo-4A/-pyrido[l,2- ]pyrimidine yielded the 2-propyloxy compound.273 Catalytic hydrogenation of the 2-alkoxy- and 2-aralkoxy-4-oxo-4A/-pyrido[l,2- ]pyrimidines was accompanied by the hydrogenolysis of the substituents in position 2.112,114... 

In Table II, kcat/Km values for four naturally occurring flavoenzymes that utilize either NADH or NADPH as substrates are listed. Comparison of these data with those of Table I shows that the oxidation ofN-hexyl-l,4-dihydronicotinamide by flavopapain IV proceeds faster than the reaction illustrated for one of the enzymes, somewhat slower than those illustrated for two of the enzymes, and much slower than that observed for bovine-heart NADH dehydrogenase. The kcat/Km values measured for the reaction of N-hexyl-l,4-dihydronicotinamide as well as those for the N-benzyl-, N-ethyl-, and N-propyl compounds... 

Chiral di- and tripropyl ethers, 59b and 60b for example, have been synthesized as shown in Figure 14.121 Complete O-alkylation of the monobenzyl ether was possible with n-propyl iodide in THF/DMF with NaH as base. The cone and the partial-cone conformers were formed in a 1 1 ratio and could be separated chroma-tographically. Alkylation with n-propyl bromide in the presence of Cs2C03 in acetone gave the di-O-propylated compound 59a, in which both propoxy groups in anti orientation, in good yield. The cleavage of the benzyl ether with trimethylsilyl bromide led to the final products 59b and 60b. 

Spectroscopic results about the interaction of the traditional spacer compound 3-aminopropyltri-ethoxysilane (APTES) with a silicon surface have already been discussed in the first part of this paper leading to the conclusion that a considerable improvement regarding the stability and durability of the amino-functionalized siloxane film is possible by using the 4-aminobutyltriethoxysilane (ABTES) rather than the propyl compound. 

The propyl compound Os3(/x-H)2(/x-CHCH2CH3)(CO)io equilibrates with a propylidene tautomer Os3(/u.-H)(CH2CH2 CH3)(CO)io at -25 °C (Scheme 26). It decomposes to propene and Os3(/x-H)2(CO)io near room temperature. Information from this and other studies shows that the alkyl/aUcylidene equilibrium shifts toward the alkylidene form with greater chain length of the alkyl. The rate of /3-hydride elimination (see -Hydride Elimination) is four times greater for the propyl compound versus the ethyl compound Os3(/u-H)R(CO)io at room temperature. ... 

TriaOcylarsine Oxides.—Only three compounds pf this type are known — the melliyl, ethyl, and n-propyl derivatives. The first two are formed by direct oxidation of the arsines by atmospheric oxygen, and the methyl compound also results when cacodyl oxide, (Me2As)20, in methyl alcohol solution is treated with methyl iodide and sodium hydroxide. The propyl derivative is formed when tetra- -propyl-arsonium hydroxide is heated in a stream of hydrogen. These oxides exhibit no add properties but are inclined to be feeWy basic, the ethyl compound yielding a nitrate, and the propyl compound a double compound with mercuric chloride. 

Isoamyl silicon trichloride is produced in a similar manner to the above, and is a colourless, transparent, fuming liquid with a penetrating odour. It boils at 46° C. at 9 mm., and has a density of 1 066. Its reactions are the same as the propyl compound. 

Tin dipropyl salts.—Normal Propyl Compounds Difltioride,—This crystallises from methyl alcohol on concentration in rosette-like groups of plates, sintering at 200° C. and melting at 204° to 205° C. 

Lead tri-n-butyl chloride is obtained from magnesium butyl iodide, and lead chloride, the product being treated with hydrogen chloride as above. It forms colourless, flat needles which melt to a clear liquid at 109° to 110° C., and have a similar solubility to the propyl compound. The hydroxide is prepared by dissolving the chloride in aqueous alcohol and shaking with silver oxide. The solution in water ha an alkaline reaction, and absorbs carbon dioxide from the air. When treated with hydrogen bromide a white precipitate of lead iri-n-butyl bromide separates, which may be recrystallised from ether or chloroform. 

A number of aluminium alkyls have been prepared A1(CH3)3 by refluxing A1 with CH3I in a nitrogen atmosphere, and the ethyl, n- and iso-propyl compounds by heating A1 with the appropriate mercury dialkyl at 110°C for 30 hours. At ordinary temperatures they are water-white liquids (the trimethyl melts at 15°C), very reactive and spontaneously inflammable in air. The trimethyl is dimeric in benzene solution and in the vapour state, the ethyl and n-propyl dimers show... 

---