152426-81-8Relevant articles and documents
Synthesis of 1,3-Amino Alcohols, 1,3-Diols, Amines, and Carboxylic Acids from Terminal Alkynes
Zeng, Mingshuo,Herzon, Seth B.
, p. 8604 - 8618 (2015/09/15)
The half-sandwich ruthenium complexes 1-3 activate terminal alkynes toward anti-Markovnikov hydration and reductive hydration under mild conditions. These reactions are believed to proceed via addition of water to metal vinylidene intermediates (4). The functionalization of propargylic alcohols by metal vinylidene pathways is challenging owing to decomposition of the starting material and catalytic intermediates. Here we show that catalyst 2 can be employed to convert propargylic alcohols to 1,3-diols in high yield and with retention of stereochemistry at the propargylic position. The method is also amenable to propargylic amine derivatives, thereby establishing a route to enantioenriched 1,3-amino alcohol products. We also report the development of formal anti-Markovnikov reductive amination and oxidative hydration reactions to access linear amines and carboxylic acids, respectively, from terminal alkynes. This chemistry expands the scope of products that can be prepared from terminal alkynes by practical and high-yielding metal-catalyzed methods.
Efficient chiral pool synthesis of the C1-C6 fragment of epothilones
Klar, Ulrich,Roehr, Bodo,Kuczynski, Frank,Schwede, Wolfgang,Berger, Markus,Skuballa, Werner,Buchmann, Bernd
, p. 301 - 305 (2007/10/03)
An efficient chiral pool synthesis of the C1-C6 fragment of epothilones starting from readily available (-)-pantolactone is described.
The formal total synthesis of epothilone A
Kalesse, Markus,Quitschalle, Monika,Claus, Eckhard,Gerlach, Kai,Pahl, Axel,Meyer, Hartmut H.
, p. 2817 - 2823 (2007/10/03)
The formal total synthesis of epothilone A is described. The key steps in the synthesis of the northern hemisphere are a Z-selective ten-membered ring-closing metathesis reaction (RCM) and the diastereoselective alkylation at C8. Aldehyde 3 is formed by introduction of the thiazole moiety by a Wittig reaction and subsequent functional group transformation. An efficient route to keto acid 5 is described.
Direct catalytic asymmetric aldol reaction
Yoshikawa, Naoki,Yamada, Yoichi M. A.,Das, Jagattaran,Sasai, Hiroaki,Shibasaki, Masakatsu
, p. 4168 - 4178 (2007/10/03)
The direct catalytic asymmetric aldol reaction using aldehydes and unmodified ketones is described for the first time herein. This reaction was first found to be promoted by 20 mol % of anhydrous (R)-LLB (L = lanthanum, L = lithium, B = (R)-binaphthol moiety) at -20 °C, giving a variety of aldol products in ee's ranging from 44 to 94%. This asymmetric reaction has been greatly improved by developing a new heteropolymetallic asymmetric catalyst [(R)-LLB, KOH, and H2O]. Using 3-8 mol % of this catalyst, a variety of direct catalytic asymmetric aldol reactions were again found to proceed smoothly, affording aldol products in ee's ranging from 30 to 93% and in good to excellent yields. Interestingly, the use of this new heteropolymetallic asymmetric catalyst has realized a diastereoselective and enantioselective aldol reaction using cyclopentanone for the first time. It is also noteworthy that a variety of aldehydes, including hexanal, can be utilized for the current direct catalytic asymmetric aldol reaction. Chiral aldehydes containing α-hydrogen including (S)-hydrocinnamaldehyde-α-d have been found to produce the corresponding aldol products with negligible racemization (0-4%) at the α-position. One of the aldol products has been successfully converted to the key synthetic intermediates of epothilone A and bryostatin 7. The possible structure of the heteropolymetallic catalyst is also discussed. Finally, mechanistic studies have revealed a characteristic reaction pathway, namely that the reaction is kinetically controlled and the rate-determining step is the deprotonation of the ketone. This is consistent with the fact that the reaction rate is independent of the concentration of the aldehyde.
Synthesis of the C1-C9 segment of epothilons
Claus, Eckhard,Pahl, Axel,Jones, Peter G.,Meyer, Hartmut M.,Kalesse, Markus
, p. 1359 - 1362 (2007/10/03)
The C1-C9 segment of epothilons was generated by an aldol reaction between chiral aldehyde 3 and ethyl ketone 4. Removal of the TBS protecting groups and debenzylation generated spiro ketal 13 which was analyzed by X-ray crystallography.
Synthetic studies on bryostatins, antineoplastic metabolites: Convergent synthesis of the C1-C16 fragment shared by all of the bryostatin family
Ohmori, Ken,Suzuki, Takayuki,Miyazawa, Kazuyuki,Nishiyama, Shigeru,Yamamura, Shosuke
, p. 4981 - 4984 (2007/10/02)
The C1-C16 fragment of bryostatins could successfully be synthesized by tandem connection of the appropriate three fragments and effective introduction of the α,β-unsaturated esters at the C13 position.
