190912-15-3Relevant articles and documents
Scalable De Novo Synthesis of Aldgarose and Total Synthesis of Aldgamycin N
Sp?th, Georg,Fürstner, Alois
, p. 7900 - 7905 (2021)
Since the accompanying study had shown that the introduction of the eponymous aldgarose sugar to the C5-OH group of the macrocyclic aglycone of aldgamycin N is most difficult, if not even impossible, the synthesis route was revised and the glycosidation performed at an earlier stage. To mitigate the “cost” of this strategic amendment, a practical and scalable de novo synthesis of this branched octose was developed. The glycoside formation required mild conditions; it commenced with the reaction of the aglycone with the trichloroacetimidate donor to give a transient orthoester, which slowly rearranged to the desired aldgaropyranoside. The presence of the polar peripheral groups in the product did not impede the selective late-stage functionalization of the macrolide ring itself: the contained propargylic alcohol entity was readily transformed into the characteristic acyloin motif of the target by a ruthenium-catalyzed trans-hydrostannation followed by a modified Chan-Lam-type coupling.
Diels-Alder Reaction of Some Trimethylsilyloxy 1,3-Dienes
Belanger, J.,Landry, N. L.,Pare, J. R.,Jankowski, K.
, p. 3649 - 3652 (1982)
The thermal condensation of five trimethylsilyloxy 1,3-dienes with ethyl mesoxalate led to dihydropyran adducts.The trimethylsilyloxy radical was then removed by hydrolysis.The Danishefsky diene 1 was used to synthesize, with acetaldehyde, the 2,3-dihydro-2-methyl-4-pyrone (18), which was also obtained by two other independent ways.
Total Synthesis of Mycinamicin IV as Integral Part of a Collective Approach to Macrolide Antibiotics
Sp?th, Georg,Fürstner, Alois
, (2022/01/13)
The total synthesis of the 16-membered macrolide mycinamicin IV is outlined, which complements our previously disclosed, largely catalysis-based route to the aglycone. This work must also be seen in the context of our recent conquest of aldgamycin N, a related antibiotic featuring a similar core but a distinctly different functionalization pattern. Taken together, these projects prove that the underlying blueprint is integrative and hence qualifies for a collective approach to this prominent class of natural products. In both cases, the final glycosylation phase mandated close attention and was accomplished only after robust de novo syntheses of the (di)deoxy sugars of the desosamine, chalcose, mycinose and aldgarose types had been established. Systematic screening of the glycosidation promoter was also critically important for success.
A Scalable Synthesis of (R,R)-2,6-Dimethyldihydro-2H-pyran-4(3H)-one
Young, Ian S.,Haley, Matthew W.,Tam, Annie,Tymonko, Steven A.,Xu, Zhongmin,Hanson, Ronald L.,Goswami, Animesh
, p. 1360 - 1368 (2015/11/02)
A scalable synthesis of (R,R)-2,6-dimethyldihydro-2H-pyran-4(3H)-one is reported. Key to this strategy is the Ti(OiPr)4-catalyzed Kulinkovich cyclopropanation of silyl protected (R)-ethyl 3-hydroxybutanoate, and subsequent oxidative fragmentati
