- Synthetic studies of complex immunostimulants from Quillaja saponaria: Synthesis of the potent clinical immunoadjuvant QS-21Aapi
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QS-21 is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing vaccine therapy clinical trials involving QS-21 as a critical adjuvant component for immune response augmentation. QS-21 is a natural product immunostimulatory adjuvant, eliciting both T-cell- and antibody-mediated immune responses with microgram doses. Herein is reported the synthesis of QS-21 Aapi in a highly modular strategy, applying novel glycosylation methodologies to a convergent construction of the potent saponin immunostimulant. The chemical synthesis of QS-21 offers unique opportunities to probe its mode of biological action through the preparation of otherwise unattainable nonnatural saponin analogues.
- Kim, Yong-Jae,Wang, Pengfei,Navarro-Villalobos, Mauricio,Ronde, Bridget D.,Derryberry, JohnMark,Gin, David Y.
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- Substrate modification as a means of enhancing the enantioselectivity of microbial reductions of β-keto esters. An (R)- or (S )-1,3,5-trihydroxypentane synthon
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The enantioselectivity of yeast-mediated reduction of 5-(benzyloxy)-3-oxopentanoate esters can be optimized by simple selection of a suitable ester alkoxy group. The resulting chiral 5-(benzyloxy)-3-hydroxypentanoates with > 95% ee can serve as either an (R)- or (S)-1,3,5-trihydroxypentane synthon for asymmetric syntheses. The synthesis of a key optically active intermediate for (S)-(-)-lipoic acid is provided as an example.
- Brooks, Dee W.,Kellogg, Rosemary P.,Cooper, Curt S.
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p. 192 - 196
(2007/10/02)
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