Direct Phosphorylation of Psilocin Enables Optimized cGMP Kilogram-Scale Manufacture of Psilocybin

Abstract

A second-generation kilogram-scale synthesis of the psychedelic tryptamine psilocybin has been developed. The synthesis was designed to address several challenges first encountered with the scale-up of previously described literature procedures, which were not optimized for providing consistent yield and purity of products, atom economy, or being run in pilot plant-scale reactors. These challenges were addressed and circumvented with the design of the second-generation route, which featured an optimized cGMP large-scale Speeter–Anthony tryptamine synthesis to the intermediate psilocin with improved in-process control and impurity removal over the three steps. Psilocin was subsequently phosphorylated directly with phosphorous oxychloride for the first time, avoiding a tedious and poor atom economy benzyl-protecting group strategy common to all previously described methods for producing psilocybin. In this report, the challenges encountered in a 100 g scale first-generation literature-based synthesis are highlighted, followed by a detailed description of the newly developed second-generation synthesis to provide over one kilogram of high-purity psilocybin under cGMP.

Psilocybin: crystal structure solutions enable phase analysis of prior art and recently patented examples

“…Alternatively, Hydrate A was prepared by recrystallization of psilocybin from 30% aqueous acetone (100 ml g À1 ) as described in Sherwood et al (2020). Hydrate A was converted to Polymorph A by drying the solid at 35-45 C under vacuum for at least 24 h and subsequently at 50-60 C under vacuum for at least 24 h. The process was carried out on a 1.2 kg scale, as described in Kargbo et al (2020). Thermal cycling of a sample of Polymorph A to 160 C for 1 h under a steady stream of nitrogen provided the PXRD pattern for Polymorph B.…”

“…More recently, synthetic process development efforts (Kargbo et al, 2020;Londesbrough et al, 2019) provided additional systematic characterization of Hydrate A and the corresponding anhydrate Polymorph A by PXRD (Fig. 1).…”

“…Given the preponderance of literature examples describing the crystallization of psilocybin from water or methanol with subsequent drying to a constant weight under vacuum with heat (Hofmann et al, 1959(Hofmann et al, , 1965Heim et al, 1965;Kuhnert-Brandsta ¨tter & Heindl, 1976;Nichols & Frescas, 1999;Londesbrough et al, 2019;Kargbo et al, 2020;Sherwood et al, 2020), we envisaged that a review of PXRD analysis on samples of bulk psilocybin produced in the years following Hoffman's first reported 1959 synthesis and crystallization would reveal results consistent with the presence of Hydrate A, Polymorph A, and/or Polymorph B phases in varying proportions, and that the so-called 'isostructural variant,' Polymorph A described in Londesbrough et al (2019) would be exposed as a mixture of Polymorph A and Polymorph B, and that the phase identified as Polymorph A 0 was really Polymorph A described herein.…”

Homebrewed psilocybin: can new routes for pharmaceutical psilocybin production enable recreational use?

“…Growing and harvesting Psilocybe mushrooms shows limited economic feasibility due to the slow production process and high product variability [ 22 ]. Current production of the psilocybin active pharmaceutical ingredient for clinical trials is achieved through traditional chemical synthesis, which despite recent advancements [ 23 , 24 ], still requires a complex, multi-step synthesis process that is hindered by low yield and high production costs [ 25–27 ]. The biosynthesis of psilocybin, made possible by recombinant DNA technology, has recently emerged as a competing technology for psilocybin production.…”

Chemoenzymatic Synthesis of 5-Methylpsilocybin: A Tryptamine with Potential Psychedelic Activity

“…The advantages of hybrid chemoenzymatic approaches to complex natural products have recently become recognized, especially when applied to late-stage modifications where the regioselectivity and efficiency of enzymes may be particularly useful . While the synthesis of 4-hydroxylated tryptamines is relatively straightforward, the subsequent 4- O -phosphorylation step has been challenging to accomplish by chemical synthesis until recently . Therefore, we sought to apply a hybrid synthetic/biocatalytic procedure developed for psilocybin gram-scale production .…”