One-pot synthesis of 5-amino-2,5-dihydro-1-benzoxepines: access to pharmacologically active heterocyclic scaffolds

A one-pot multibond-forming process involving a thermally mediated Overman rearrangement and a ring closing metathesis reaction of allylic trichloroacetimidates bearing a 2-allyloxyaryl group has been developed for the synthesis of 5-amino-substituted 2,5-dihydro-1-benzoxepines. Chemoselective reduction and functionalization of these compounds allowed access to a range of pharmacologically active 5-amino-2,3,4,5-tetrahydro-1-benzoxepine scaffolds

The development of one-pot tandem reactions for the synthesis of polycyclic y-lactams

A novel tandem process has been developed for the stereoselective synthesis of bicyclic γ-lactams. Treatment of an allylic alcohol with trichloroacetonitrile, in the presence of DBU, affords the corresponding allylic trichloroacetimidate. This is then subjected to a tandem Overman rearrangement/RCM/Kharasch cyclisation, forming the desired bicyclic lactam in high yield and high enantiomeric excess. Overall, the one-pot tandem process involves three mechanistically distinct processes catalysed by palladium(II) (step 1) and Grubbs 1st generation catalyst (steps 2 and 3). The use of a thermal Overman rearrangement in tandem with the Grubbs catalysed RCM/Kharasch cyclisation was also investigated. Furthermore, a microwave-assisted tandem process was developed which resulted in the accelerated synthesis of the desired bicyclic γ-lactams. A two-step tandem process was then developed for the synthesis of bicyclic allylic amides, a closely related core unit to that found in a number of important commercially available drugs. Finally, progress has been made towards the total synthesis of (±)-deethylibophyllidine, which will utilise a tandem RCM/Kharasch cyclisation to construct the C and D rings of the natural product

Preparation of amino-substituted indenes and 1,4-dihydronaphthalenes using a one-pot multireaction approach: total synthesis of oxybenzo[c]phenanthridine alkaloids

Allylic trichloroacetimidates bearing a 2-vinyl or 2-allylaryl group have been designed as substrates for a one-pot, two-step multi-bond-forming process leading to the general preparation of aminoindenes and amino-substituted 1,4-dihydronaphthalenes. The synthetic utility of the privileged structures formed from this one-pot process was demonstrated with the total synthesis of four oxybenzo[c]phenanthridine alkaloids, oxychelerythrine, oxysanguinarine, oxynitidine, and oxyavicine. An intramolecular biaryl Heck coupling reaction, catalyzed using the Hermann–Beller palladacycle was used to effect the key step during the synthesis of the natural products

Molar efficiency

The concept of molar efficiency is introduced as a new metric to enable assessment of reaction efficiency in discovery medicinal chemistry. Calculations from molar units enable cross-comparison of the broad range of transformations employed in discovery-phase medicinal chemistry research and is proposed to facilitate identification of more sustainable synthetic transformations

Development of a solvent selection guide for aldehyde-based direct reductive amination processes

A range of alternative, more environmentally conservative solvents have been evaluated for use within the direct reductive amination reactions of aldehydes using borane-based reductants. The data generated has been used to develop a guide to facilitate replacement of less desirable chlorinated solvents, such as DCE, from these widely used synthetic processes

Molar Efficiency: A Useful Metric To Gauge Relative Reaction Efficiency in Discovery Medicinal Chemistry

The concept of molar efficiency is introduced as a new metric to enable assessment of reaction efficiency in discovery medicinal chemistry. Calculations from molar units enable cross-comparison of the broad range of transformations employed in discovery-phase medicinal chemistry research and is proposed to facilitate identification of more sustainable synthetic transformations

A three-step tandem process for the synthesis of bicyclic gamma-lactams

A one-pot, three-step tandem process has been developed for the direct synthesis of functionalised bicyclic [3.3.0], [4.3.0] and [5.3.0] gamma-lactams from simple allylic trichloroacetimidates. The process involves a palladium(II) mediated Overman rearrangement followed by the use of Grubbs first generation complex which catalyzes both a ring closing metathesis reaction and a Kharasch cyclization. As well as exploring the scope of this process for the synthesis of a range of functionalised bicyclic g-lactams, the use of chiral palladium(II) catalysts during the Overman rearrangement for the enantioselective synthesis of the bicyclic g-lactams is also demonstrated