The Total Synthesis of Allosamidin. Expansions of the Methodology of Azaglycosylation Pursuant to the Total Synthesis of Allosamidin. A Surprising Enantiotopic Sense for a Lipase-Induced Deacetylation

Abstract

Allosamidin, recently isolated from mycelial extracts of Streptomyces sp. 1713, is a powerful and selective chitinase inhibitor. The total synthesis of allosamidin is described herein. The electric eel acetylcholinesterase-mediated enantioselective hydrolysis of (trans,trans)-2-(benzyloxy)cyclopentene-1,3-diol diacetate accessed a monoacetyl derivative. Five additional steps produced a protected version of the aglycon (“allosamizoline”) sector of allosamidin. An allal derivative stereoselectively reacted with benzenesulfonamide in the presence of a halonium source to afford a 2β-halo-1α-sulfonamidohexose. Treatment of this product with a strong base generated an intermediate 1,2-sulfonylaziridine, which was trapped with a protected allal derivative to provide a disaccharide glycal. Reiteration of this scheme gave access to the required trisaccharide. Following deprotection, the total synthesis of allosamidin was accomplished. In addition, the method, with modification, gave access to several allosamidin analogs.

Enantioselective preparation of (R) and (S)-3-hydroxycyclopentanone by kinetic resolution

“…Those with small and few substituents, such as cyclopent-4-ene-1,3-diyl diacetate (80% yield, 20.5% ee) [34], cyclohex-2-en-1-yl acetate [35], 4-hydroxycyclopent-2-en-1-one (E = 11) [36], 4-hydroxy-2-methyl-2-cyclopentenone (60% yield, 60% ee) [37], 3-bromocyclopent-2-enol [38] give less enantiopure products. An exception is the meso compounds [43][44][45][46][47][48][49], however here the stereo differentiation is based on a different principle.…”

Recent trends in the synthesis of O-glycosides of 2-amino-2-deoxysugars

“…Additionally, disaccharide 49 can be employed in iterative elongation of the oligosaccharide sequence, since the double bond could be sulfonamidated followed by glycosidation, etc. To date, the potency and versatility of the sulfonamide glycosylation reaction has been applied to the synthesis of sialyl Lewis X antigen and antigenic determinants, 99,100 asparagine-linked N-protected glycopeptides and N-linked glycopeptides, 101,102 stagespecific embryonic antigen-3 (SSEA-3), 103 allosamidin, 104 human breast tumor (Globo-H) antigen, 105 asialo GM 1 , 106 KH-1 (adenocarcinoma) antigen, 107 mucin-related F1a antigen, 108 and the core pentasaccharide of N-linked 109 glycoproteins.…”

2-(Trimethylsilyl)ethanesulfonamide (TMS(CH2)2SO2NH2 or SES-NH2) - A Sulfonamidation Agent With Multiple Qualities

“…4 It should be used with carefull precaution, because it can be irritating to the eyes, the skin and the respiratory system.…”