Total Synthesis of 3′,5′‐C‐Branched Nucleosides.

Abstract

Total Synthesis of 3',5'-C-Branched Nucleosides. -A novel route to title nucleosides, in particular nucleoside (IX), is presented. Key reactions are the aldehyde alkynylation to give propargyl alcohol (III), and the one-pot Ireland-Claisen rearrangement/iodolactonization reactions to give the desired trans-lactone (VIII). The cis-lactone (VII), also formed in remarkable amounts as by-product, can be isomerized into the trans-isomer (VIII). The racemic route can be performed as asymmetric variant, as is demonstrated by preparation of nonracemic propargyl alcohol (S)-(III) from alkyne (I) and aldehyde (II) in the presence of zinc triflate and optically active N-methylephedrine. -(ROZNERS*, E.; XU, Q.; Org. Lett. 5 (2003) 21, 3999-4001; Dep. Chem., Northeast. Univ.,

Asymmetric syntheses of four stereoisomers of 13‐hydroxy‐14‐methylhexadecanoic acid as potential antibacterial agents

“…The data that support the findings of this study are openly available in figshare at http://doi.org/10.1002/chir.23352, reference number [1–43].…”

“…The enantioselective synthesis of (13 R , 14 S )‐ 1 was first targeted (Scheme 3). The selective reduction of lactone (3 S , 4 R )‐ 4 with diisobutylaluminum hydride (DIBAL‐H) gave the aldehyde homoaldol, which was easily reduced to diol (3 S ,4 R )‐ 5 by sodium borohydride (NaBH 4 ) in 91% yield over 2 steps 34,35 . The selective protection of primary alcohol at (3 S ,4 R )‐ 5 with tert ‐butylchlorosilane chloride (TBSCl) 36 and then protection of the second alcohol with 4‐methoxybenzyl bromide (PMBBr), 37 followed by deprotection of the TBS group of primary alcohol with pyridinium 4‐toluenesulfonate (PPTS) afforded PMB‐ether (3 S ,4 R )‐ 6 (25% yield 3 steps) 38 .…”

Identification of Novel S-Adenosyl-l-Homocysteine Hydrolase Inhibitors through Homology-Model-Based Virtual Screening, Synthesis, and Biological Evaluation

“…Next, compounds 13a , 13b , 13c , and 13d were synthesized from 12 under different conditions. For the syntheses of 13a and 13b , compound 12 was coupled with cytosine and uracil, respectively, in the presence of TMSOTf to give 13a in 75% and 13b in 72% yields. The modified nucleoside 13c was obtained from 12 via SnCl 4 mediated glycosylation of unprotected adenine, whereas 13d was synthesized from 12 using a protocol developed by Zou and Robins. , Finally deprotection of Fmoc followed by in situ protection of the resulting amine with (Boc) 2 O afforded compounds 2 – 5 in 83–87% yields.…”

Auto Machine Learning Assisted Preparation of Carboxylic Acid by TEMPO‐Catalyzed Primary Alcohol Oxidation

“…On one hand, TEMPO is a stable, cheap, and readily available reagent. [ 11‐26 ] On the other hand, safe and bulk oxidants were allowed for TEMPO‐mediated oxidation, making it a mild, efficient, and environmental‐friendly method (Figure 1A). Perhaps alcohol oxidation was considered as a mature technology far from the forefront of organic synthesis, it remains challenging to select productive conditions for unseen alcohols, especially those with complex structures or oxidation‐sensitive functional groups.…”