Chiral Bicyclic Tetramates as Non‐Planar Templates for Chemical Library Synthesis

Abstract

Chemoselective Dieckmann cyclization reactions may be used on oxazolidine and thiazolidine templates derived from various aldehydes to access bicyclic tetramates, which have potential as templates for chemical library construction. Bioassay against Staphylococcus aureus and Escherichia coli showed that these systems have little or no intrinsic antibacterial bioactivity.

Purple acid phosphatase inhibitors as leads for osteoporosis chemotherapeutics

“…1 H NMR (500 MHz, CDCl 3 ) δ 3.08 (dd, J 8.9 Hz, J 10.3 Hz) and 3.20 (dd, J 5.5 Hz, J 10.7 Hz) integrate for 1H, 3.36 (dd, J 7.1 Hz, J 10.7 , 128.2, 128.7, 130.1, 132.9, 159.3, 159.8, 171.6, 172.3. NMR spectra are in agreement with those reported by Anwar and Moloney[63].…”

Synthesis of 3-acyltetramates by side chain manipulation and their antibacterial activity

“…[1][2][3] Several are of interest for their antibacterial activity, notable examples being equisetin, 4 reutericyclin, 5 kibdelomycin, 6 and streptolodygin, 7 and significant progress in the development of synthetic routes to such systems 8 and their analogues has recently been made. 3 Interestingly, methodology for the general preparation of β-tricarbonyl systems is scarce, 9 and we have recently reported methodology providing access to highly substituted 3-acyltetramates, which relies upon Dieckmann cyclisation of templates 2 derived from serine, 10 threonine 11 or cysteine, 12 the chemoselectivity of which can be controlled by judicious use of reaction conditions and substituents to give products 3 and/or 4 (Scheme 1). 13 Moreover, we have established a reliable approach for the introduction of diverse 3-acyl groups into either of 3 or 4, 14 and this permits rapid generation of chemical diversity around the core tetramate scaffold.…”

Fused-Ring Oxazolopyrrolopyridopyrimidine Systems with Gram-Negative Activity

“…Our approach began with tetramates 3a–c , which we have reported previously, to be available in enantiopure form from the esters of serine 1a , threonine 1b , and cysteine 1c (Scheme 1) [17,18]; this outcome arises as a result of the selective formation of cis -oxa(thia)zolidines 2a–c , which chemoselectively cyclise to the product tetramates under basic conditions. Reaction of each of these with trimethyl orthoformate and para -bromoaniline (using a protocol which has been recently reported [19]) gave the corresponding enamines 4a–c ; these were obtained as E/Z mixtures, and the identity of the major one as Z was established by dihedral-angle-dependent coupling constants [20] from HMBC NMR experiments; thus, the intensity of the coupling between the exocyclic vinylic proton and C-5 is greater than that with C-7 in major product ( Z )-4a , and vice versa in the minor product ( E )-4a , clearly indicating the double bond geometry in each case (Figure 1).…”

“…The starting materials 1a–c , 2a–c , and 3a–c were all prepared using reported methods [17,18,30]. The compounds 4a and 6a have been previously reported [16], but were prepared here using slightly different methods (see below).…”