Carbamate-directed hydroboration: enantioselective synthesis of the excitatory amino acid 1-aminocyclopentane-1,3-dicarboxylic acid

Synthesis and Anticonvulsant Activity of Novel Bicyclic Acidic Amino Acids

“…To a stirred solution of 8 18 (1.25 g, 4.9 mmol) in THF (20 mL) were sequentially added 4-(dimethylamino)pyridine (60 mg, 0.49 mmol) and a THF solution (10 mL) of di-tert-butyl dicarbonate (1.6 g, 7.35 mmol). The mixture was refluxed for 6 days, and di-tert-butyl dicarbonate (0.5 equivalents) was added every day.…”

“…Dipolarophile 8 was prepared according to the procedure reported in the literature, 18 whereas 9 was synthesized by refluxing a THF solution of 8 with excess di-tert-butyl dicarbonate in the presence of 4-(dimethylamino)pyridine. The cycloaddition step, carried out on dipolarophile 8, produced a mixture of the two stereoisomers (()-10 and (()-11 in a 84:16 ratio.…”

“…The key step in the synthesis of target compounds (±)- 6 and (±)- 7 is represented by the 1,3-dipolar cycloaddition of ethoxycarbonylformonitrile oxide, generated in situ by treatment of ethyl 2-chloro-2-(hydroxyimino)acetate with a base, to a suitably protected 1-amino-cyclopent-3-enecarboxylic acid ( 8 and 9 ) (Scheme ). Dipolarophile 8 was prepared according to the procedure reported in the literature, whereas 9 was synthesized by refluxing a THF solution of 8 with excess di- tert -butyl dicarbonate in the presence of 4-(dimethylamino)pyridine. The cycloaddition step, carried out on dipolarophile 8 , produced a mixture of the two stereoisomers (±)- 10 and (±)- 11 in a 84:16 ratio.…”

Enantioselective desymmetrisation

“…Hodgson has recently reported a carbamate-directed enantioselective hydroboration en-route to the synthesis of 1-aminocyclopentane-1,3-dicarboxylic acid. 59 A catalysed intramolecular hydrosilylation of achiral dienes using a Rh()-DIOP {4,5-bis[(diphenylphosphino)methyl]-2,2dimethyl-1,3-dioxolane} complex followed by oxidative workup has been used to prepare enantiomerically enriched diols. 60 For the desymmetrisation of protected di(prop-2-enyl)meth- The base promoted addition of a C 2 -symmetric diol has been employed to effectively desymmetrise 1,2-disulfonyl substituted alkenes.…”

Efficient Method for the Synthesis of an Important Precursor of Constrained Peptides

“…Subsequent hydrolysis of the coupling product 2 in absolute ethanol with concentrated hydrochloric acid followed by protection of the amino group using di-tert-butyl dicarbonate led to the formation of the Boc derivative 4 in 69% yield. The last step of this synthesis involved a ring closing metathesis (RCM) reaction by treatment of the previous This synthesis constitutes an efficient alternative to the method described in the report by Hodgson et al [8][9]. Furthermore, the use of a tert-butyl group as a protecting group may be advantageous since it can be easily removed under mild conditions [10][11].…”