De Novo Asymmetric Synthesis of Anthrax Tetrasaccharide and Related Tetrasaccharide

Abstract

A de novo asymmetric approach to the natural product anthrax tetrasaccharide 1 and an analogue 2 with an anomeric hexyl azide group has been developed from acetylfuran. The construction of the tetrasaccharide was achieved by a traditional [3 + 1] glycosylation strategy. An iterative diastereoselective palladium-catalyzed glycosylation, Luche reduction, diastereoselective dihydroxylation, and regioselective acylation were employed for the assembly of the L-rhamno-trisaccharide building block. The anthrose building block also required a palladium-catalyzed azide allylation and a triflate inversion to set the gluco-stereochemistry in addition to Luche reduction and dihydroxylation.

Merremoside D: De Novo Synthesis of the Purported Structure, NMR Analysis, and Comparison of Spectral Data

“…Because the route uses asymmetric synthesis, it offers equal efficiency to access to various all D-, all L- and mixed D/L-isomer. 9 Herein, we disclose our successful efforts at the synthesis of the purported structure of merremoside D.…”

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

“…When Mitsunobu chemistry fails, O’Doherty and co-workers have achieved hydroxy group inversion by triflation and displacement using sodium nitrite [39]. Cyclic sulfate 32b was exposed to sodium nitrite in DMF; the mixture was heated at reflux until completion of the reaction was confirmed by 19 F NMR.…”

C5′-Alkyl Substitution Effects on Digitoxigenin α-l-Glycoside Cancer Cytotoxicity

“…19 The absolute l -sugar stereochemistry was installed via an enantioselective Noyori asymmetric reduction 20. The resulting furfural alcohol 15a (> 99% ee ) was converted to the corresponding pyranone via an Achmatowicz oxidative rearrangement, and a stereodivergent Boc-protection to yield easily separable 4 to 1 ratio of α/β-mixtures of Boc-pyranones in good overall yield (60–70%) 21…”