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Book II of PiHKAL: A Chemical Love Story, by Alexander & Ann Shulgin #47: 2C-T-15
#47 2C-T-15: SESQUI; 2,5-Dimethoxy-4-cyclopropylthiophenethylamine

#47 2C-T-15 SYNTHESIS: To a solution of 3.3 g of KOH pellets in 150 mL hot MeOH, there was added 10 g 2,5-dimethoxythiophenol (see recipe for 2C-T-2 for its preparation) followed by 10 g 1-bromo-3-chloropropane. The reaction was exothermic, and immediately deposited white solids of KCl. The reaction mixture was warmed for a few min on the steam bath, and then quenched in H2O. The basic reaction mixture was extracted with 3×75 mL CH2Cl2. The pooled extracts were stripped of solvent under vacuum. The residual oil was distilled at 145–155 °C at 0.2 mm/Hg to give 16.5 g of 2,5-dimethoxyphenyl 3-chloropropyl sulfide as a clear, colorless oil.

A solution of the lithium amide of 2,2,6,6-tetramethylpiperidine was prepared by the addition of 20 mL of 2.6 M butyllithium in hexane to a well stirred hexane solution of the piperidine in 100 mL hexane, under an atmosphere of He. The reaction was exothermic, formed a white solid precipitate, and was allowed to continue stirring for a few min. There was then added 6.5 g 2,5-dimethoxphenyl 3-chloropropyl sulfide, and a strongly exothermic reaction ensued. This was stirred for 30 min and then poured into dilute H2SO4 (the progress of the reaction must be followed by TLC, silica gel plates, CH2Cl2:petroleum ether 50:50 to determine when it is done; in one run over 2 h were required for completion of the reaction). The organic phase was separated, and the aqueous phase extracted with 3×75 mL EtOAc. The combined organic phases were washed first with dilute NaOH, then with dilute HCl, then the solvents were removed under vacuum. The residue was distilled to provide 2,5-dimethoxyphenyl cyclopropyl sulfide as a pale yellow liquid that boiled at 100–115 °C at 0.1 mm/Hg. The use of other bases to achieve this cyclization were less successful. Incomplete cyclization resulted from the use of lithium diisopropyl amide and, if the conditions were made more vigorous, there was dehydrohalogenation to the allyl sulfide. An unexpected difficulty was that the allyl sulfide (from elimination) and the 3-chloropropyl sulfide (starting material) behaved in an identical manner on TLC analysis. They were easily separated, however, by GC analysis.

A completely different approach to the synthesis of this sulfide was explored through the reaction of cyclopropyllithium with an aromatic disulfide, thus avoiding the base-promoted cyclization step. A solution of 2.6 g di-(2,5-dimethoxyphenyl)disulfide (from 2,5-dimethoxythiophenol and hydrogen peroxide, bp 220–230 °C at 0.3 mm/Hg) was made in anhydrous Et2O, and well stirred. In a separate flask, under an atmosphere of He, 4 mL of 2.6 M butyllithium was added to a solution of 1.2 g cyclopropyl bromide in 20 mL anhydrous Et2O. This mildly exothermic combination turned a bit cloudy, was stirred for 1 h, then transferred with an air-tight syringe to the above-described Et2O solution of the aromatic disulfide. A heavy precipitate formed, and stirring was continued for an additional 0.5 h. The reaction mixture was then poured into H2O, the layers separated, and the aqueous phase extracted with CH2Cl2. The extracts were pooled, washed with dilute aqueous KOH, and the solvents removed under vacuum. Distillation gave 0.7 g of 2,5-dimethoxyphenyl cyclopropyl sulfide with identical gas chromatographic behavior to the sample prepared by the cyclization of the chloropropylthio compound.

A mixture of 7.2 g POCl3 and 6.7 g N-methylformanilide was heated on the steam bath until it was claret red. To this there was added 4.5 g of 2,5-dimethoxyphenyl cyclopropyl sulfide, and the exothermic combination heated on the steam bath for about 5 min. The deep red, bubbling reaction mixture was added to 150 mL H2O and stirred until all oils had been converted into loose solids. These were then removed by filtration, washed with H2O, and sucked as dry as possible. They were dissolved in boiling MeOH which, after cooling in an ice-bath, deposited yellow crystals of 2,5-dimethoxy-4-(cyclopropylthio)benzaldehyde that weighed 3.43 g after air drying, and had a mp of 97–99 °C. Anal. (C12H14O3S) C,H.

To a solution of 3.0 g 2,5-dimethoxy-4-(cyclopropylthio)benzaldehyde in 40 g of nitromethane there was added 0.2 g of anhydrous ammonium acetate, and the mixture was heated on the steam bath for 3 h. The excess nitromethane was removed under vacuum yielding 3.4 g orange crystals. These were recrystallized from 150 mL boiling IPA containing a little toluene. After cooling, filtering, and air drying there were obtained 2.75 g of 2,5-dimethoxy-4-cyclopropylthio-β-nitrostyrene as pumpkin-colored crystals with a mp of 159–160 °C. Anal. (C13H15NO4S) C,H.

A solution of LAH (40 mL of a 1 M. solution in THF) was cooled, under He, to 0 °C with an external ice bath. With good stirring there was added 1.05 mL 100% H2SO4 dropwise, to minimize charring. This was followed by the addition of 2.5 g 2,5-dimethoxy-4-cyclopropylthio-β-nitrostyrene in 40 mL anhydrous THF over the course of 15 min. There was an immediate loss of color. After a few min further stirring, the temperature was brought up to a gentle reflux on the steam bath and held there for 2 h. After recooling, there was added IPA (to destroy the excess hydride) followed by sufficent 15% NaOH to give a white granular character to the oxides, and to assure that the reaction mixture was basic. The reaction mixture was filtered, and the filter cake washed with THF. The filtrate and washes were stripped of solvent under vacuum providing a yellow oil that was treated with dilute H2SO4. This produced a flocculant white solid, apparently the sulfate salt of the product. This was washed with 4×75 mL CH2Cl2 which removed most of the yellow color. The aqueous phase was made basic with aqueous NaOH and extracted with 3×75 mL CH2Cl2. Removal of the solvent under vacuum gave a light yellow colored oil that was distilled at 0.3 mm/Hg. The fraction boiling at 140–150 °C was a colorless, viscous oil that weighed 1.97 g. This was dissolved in a few mL IPA, and neutralized with concentrated HCl forming immediate cottage cheese-like crystals of the hydrochloride salt. This was diluted by suspension in anhydrous Et2O, removed by filtration, and air dried to give 1.94 g of 2,5-dimethoxy-4-cyclopropylthiophenethylamine hydrochloride (2C-T-15) that had a mp of 203–5-204.5 °C. Anal. (C13H20ClNO2S) C,H.

DOSAGE: greater than 30 mg.

DURATION: several hours.

QUALITATIVE COMMENTS: (at 30 mg) “I was somewhere between a threshold and a plus one for several hours, and appeared to be quite talkative in the evening.”

EXTENSIONS AND COMMENTARY: The commonly used name for 2C-T-15, during its synthesis, was SESQUI. The general name for a 15-carbon terpene is sesquiterpene, from the Latin prefix for one and a half. The active level of 2C-T-15 is not known. The highest level yet tried was 30 milligrams orally, and there had been threshold reports pretty regularly all the way up from 6 milligrams. But no definite activity yet. This compound is isosteric with the isopropyl group as seen in the analogous compound 2C-T-4 (the three carbons are in exactly the same positions, only the electrons are located differently) and it is a little surprising that the potency appears to be considerably less. Just over 20 milligrams of the latter compound was overwhelmingly psychedelic.

The entire mini-project of hanging cyclic things onto the sulfur atom was an interesting problem. This is the three carbon ring. The six carbon ring (the cyclohexyl homologue) was discussed as 2C-T-5 in the recipe for of ALEPH-2. The cyclobutyl and cyclopentyl homologs were assigned the names of 2C-T-18 and 2C-T-23, respectively, and their preparations taken as far as the nitrostyrene and the aldehyde stages, respectively, before the project ran out of steam.

Towards the cyclobutyl homologue, a solution of 2,5-dimethoxythiophenol and cyclobutyl bromide in DMSO containing anhydrous potassium carbonate was stirred for several hours at room temperature and yielded 2,5-dimethoxyphenyl cyclobutyl sulfide as a white oil that boiled at 135–140 °C at 0.3 mm/Hg. Anal. (C12H16O2S) C,H. This was brought to react with a mixture of phosphorus oxychloride and N-methylformanilide producing 2,5-dimethoxy-4-(cyclobutylthio)benzaldehyde that had a melting point of 108–109.5 °C from MeOH. Anal. (C13H16O3S) C,H. Coupling with nitromethane in the presence of ammonium acetate produced 2,5-dimethoxy-4-cyclobutylthio-β-nitrostyrene as lustrous orange crystals from boiling acetonitrile, melting point 160–161 °C. Anal, (C14H17NO4S) C,H. This will some day be reduced to 2,5-dimethoxy-4-cyclobutylthiophenethylamine hydrochloride, 2C-T-18.

Towards the cyclopentyl homologue, a solution of 2,5-dimethoxythiophenol and cyclopentyl bromide in DMSO containing anhydrous potassium carbonate was stirred for several hours at room temperature and yielded 2,5-dimethoxyphenyl cyclopentyl sulfide as a white oil that boiled at 135–145 °C at 0.3 mm/Hg. This was brought to react with a mixture of phosphorus oxychloride and N-methylformanilide producing 2,5-dimethoxy-4-(cyclopentylthio)benzaldehyde as yellow crystals from MeOH. This will some day be converted to the nitrostyrene and then reduced to 2,5-dimethoxy-4-cyclopentylthiophenethylamine hydrochloride, 2C-T-23.

Page updated 30 March 2012 · This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License ·

About PiHKAL • info

This version of Book II of PiHKAL is based on the Erowid online version, originally transcribed by Simson Garfinkle and converted into HTML by Lamont Granquist. I drew also on “Tyrone Slothrop’s” (Unfinished) Review of PIHKAL to enumerate the many analogues mentioned in PiHKAL but not described at length. Still others remain to be added.

I have tried here to expunge any artifacts introduced by the earlier transcriptions and restore most of the typographic niceties found in the printed edition. I’ve also made minor changes to some chemical names in line with current nomenclature practice, and in the hope of aligning with more readers’ searches. Typically the change is little more than expanding a prefix and setting it in italics. The errata and changes page has further details.

Cautionary Note

“At the present time, restrictive laws are in force in the United States and it is very difficult for researchers to abide by the regulations which govern efforts to obtain legal approval to do work with these compounds in human beings.

“No one who is lacking legal authorization should attempt the synthesis of any of the compounds described in these files, with the intent to give them to man. To do so is to risk legal action which might lead to the tragic ruination of a life. It should also be noted that any person anywhere who experiments on himself, or on another human being, with any of the drugs described herein, without being familiar with that drug’s action and aware of the physical and/or mental disturbance or harm it might cause, is acting irresponsibly and immorally, whether or not he is doing so within the bounds of the law.”

Alexander T. Shulgin

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