I -Bromopentane

Reaction of epichlorohydrin with sodium methanethiolate gave l,3-bi (methylthio)-2-propanol, which was converted to the sodio derivative and methylated to afford l,3-bis(methylthio)-2-methoxypropane. Finally, treatment with LDA (1 equiv.) resulted in elimination of methanol to give l,3-bis(methyl-thio)propene, whereas reaction with 2 equiv. of LDA gave bis(methylthio)allyllithium, which reacted with I bromopentane furnishing l,3-bis(methylthio)-l-octene, which in turn was converted by hydrolysis with mercury(II) chloride to rra/is-2-octenal (Scheme 14). 

Table I. Reaction of 1-Bromopentane with Various Nucleophiles under PTC Conditions ...

I) 1-Bromo-l-methylcyclohexane (II) 2-Chloro-2-methylbutane (III) 2,2,3-TrImethyl-3-bromopentane. 

Treatment of RuCl3 xH20 with Hacac gives tra i-[Ru(acac)2Cl2] (the first trani-bis(acac) complex to have been made). The complex anion is a precursor to a range of Ru, Ru, and Ru tra 5 -bis(acac) complexes including tra w-[Ru (acac)2L2] where L = MeCN or pyrazine (pyz) the cis analogs result from direct reaction between [Ru(acac)3] and MeCN or pyz (see also Section 5.5.3.4.1). The reaction of [Ru(acac)3] with molten 1,3-diaminobenzene yields complexes (8)-(10). Their formation involves Ru-mediated oxidative di- and trimerization of 1,3-diaminobenzene. Structural data for [Ru(acac)3] and [Ru(3-Bracac)3] (H-3-Bracac = 3-bromopentane-2,4-dione)... 

The racemic stereoisomer (16b) of monomorine I has been stereoselectively synthesized (416). Thus, successive bis-alkylations of l-methoxycarbonyl-3-pyrroline (379) gave tranj-2,5-diaIkylpyrroIine (381) as a 1 1 mixture of 4 -bromopentane isomers. N-Decarbomethoxylation gave the bicyclic compound... 

Synthesis (Freed and Potoski (American Home), 1971 Freed, 1973 Kleemann et al., 1999,) Dezocine is prepared through the following sequence The condensation of 1-methyl-7-methoxy-2-tetralone with 1,5-di-bromopentane by means of NaH or potassium tertbutylate affords 1 -(5-bromopentyl)-1 -methyl-7-methoxy-2-tetralone this product is cyclized with NaH to give 5-methyl-3-methoxy-5,6,7,8,9,10,11,12-octahydro-5,11 -methano-benzocyclodecen-13-one i. The ketone i, by reaction with hydroxylamine hydrochloride in pyridine, is converted into its oxime ii, which is reduced with H2 over Raney Ni to a mixture of isomeric amines which were separated by crystallization of the HCI salts giving 5-a-methyl-3-methoxy-5,6,7,8,9,11 a, 12-octahydro-5,11 -methanobenzo-cyclodecen-13p-amine, which is finally cleaved with concentrated HBr. 

In a 5-I. flask, placed on a steam bath and fitted with a mechanical stirrer, a separatory funnel, a thermometer well (Note 1) and a calcium chloride tube, is placed 182 g. (7.5 moles) of magnesium turnings. To this is added a crystal of iodine and 100 cc. of a solution of 1133 g. (7.5 moles) of 2-bromo-pentane (Note 2) in 750 g. of -butyl ether (Note 3). The stirrer is started and the flask is heated with steam until the reaction starts. This may take from fifteen minutes to one hour, but the flask must be watched quite closely because the reaction, when once started, is very vigorous and evolves a large amount of heat. As soon as the reaction has started, 750 g. of w-butyl ether is added and then the balance of the solution of 2-bromo-pentane in w-butyl ether is added at such a rate that the temperature is kept at 50-60°. External cooling is used in order to allow more rapid addition of the 2-bromopentane. After addition is complete (about three hours), the mixture is heated on a steam bath for one hour. 

Alkyl halides such as 1-chlorocyclohexane, 1-bromopentane and 1-iodohexane associate with silver and the spectra shift in the presence of the binuclear reagents. The shifts for the organohalides were in the order I > Br > Cl, reflecting the relative softness and hence relative binding abilities of the halides to silver. Some organohalides were reactive with silver such that a silver halide precipitate formed . ... 

The synthesis of sodium secobarbital is described in the patent2. Propyl-methyl-carbinol (I) is treated with anhydrous gaseous HBr, at a low temperature to reduce isomer formation, to produce 2-bromopentane (II). Malonic ester (III) is added to a solution of sodium in alcohol. This is followed by a slow addition of II. The solvent is removed by... 

Fig. 12. Adam-Gibbs plots of the dielectric relaxation time of 2-methyltetrahydrofuran (2-MTHF) and 3-bromopentane (3-BP) versus (Tsconi) . The lines are VTF fits, 7 fus is the fusion temperature, and Tb is the temperature below which the VTF equation applies. /I ag and Avf are prefactors in the Adam-Gibbs and VTF equations, respectively. Tk is the calorimetri-cally determined Kauzmann temperature, and To is the VTF singular temperature, which were set equal in the VTF (line) fits. (Reprinted with permission from R. Richer and C. A. Angell. Dynamics of glass-forming liquids. V. On the link between molecular dynamics and configurational entropy. J. Chem. Phys. (1998) 108 9016. Copyright 1998, American Institute of Physics.)...

Internal alkenes react less readily with RBeH. The reactivity of 1-pentene to EtHBe-n OEtj is >200 times that of 2-pentene the trialkylated ethene, 2-methylbut-2-ene, is inactive to addition of RBeH (R = Et, i-Bu) at 84°C and reacts only slowly with the more active, base-free i-BuBeH at 110°C (see Table 1) . Beryllium migrates to the end of the carbon chain as shown by the bromination of the products from 2-pentene and EtBeH 82% 1-bromopentane, 12% 2-bromopentane and 6% 3-bromopentane. ... 

For replacement of alcoholic OH by Br it is advisable to use the /7-toluenesulfonate method when other methods lead to isomerization. Secondary alcohols do not suffer rearrangement of the carbon skeleton when Br is substituted for their OH group by the /7-toluenesulfonate method 867 this is the only way to obtain pure 2- or 3-bromopentane.866 [l-14C]Allylalcohol yields only [l-14C]allyl bromide by the toluenesulfonate method,966 i.e., there is no allylic rearrangement. 

Diethyl malonate on reaction with sodium metal gives rise to sodium malonic ester which on treatment with ethyl bromide results into the formation of diethyl ester of ethyl malonic acid with the elimination of hydrobromic acid. The resulting ester on further reaction with 2-bromopentane gives the desired eompound, i.e., diethyl ester of ethyl (1-methyl butyl) malonic acid which on subsequent treatment with thiourea forms thiopental with the elimination of two moles of ethanol. Ultimately, the enol-iorm of thiopental when reaeted with a ealeulated amoimt of sodium hydroxide, it gives thiopental sodium. 

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