Stereocontrolled total synthesis of Antibiotic A-23187 (calcimycin)

Claisen Rearrangement of Aliphatic Allyl Vinyl Ethers from 1912 to 2012: 100 Years of Electrophilic Catalysis

“…Based on initial attempts to exploit the capability of the Claisen rearrangement of acyclic allyl vinyl ethers 'as the means of transferring the chirality of a carbon-oxygen bond to that of a nonadjacent carbon-carbon bond', 49,50 the first example of a largely successful self-immolative 1,3-and 1,4-chirality transfer was, to the best of our knowledge, published by Ireland (Scheme 13). 51…”

Sulfonated Ordered Nanoporous Carbon (CMK-5-SO3H) as an Efficient and Highly Recyclable Catalyst for the Silylation of Alcohols and Phenols with Hexamethyldisilazane (HMDS)

“…This method is also efficient for the silylation of secondary alcohols (Table 1, entries 12-17). Meanwhile, primary and secondary aliphatic alcohols were readily transformed to their corresponding silyl ethers in high yields (Table 1, entries [10][11][12][13][14][15][16]. Phenol, 4-chlorophenol, 3-nitrophenol, 3,5-dimethylphenol and 2-hydroxy benzaldehyde were also silylated in an efficient manner in excellent yields ( To demonstrate whether the protection of alcohols catalyzed by CMK-5-SO 3 H is actually proceeding in a heterogeneous pathway, the silylation of benzyl alcohol was carried out in dichloromethane in which the catalyst was filtered off at approximately 50% conversion and the resulting clear solution stirred for additional time in the absence of the solid.…”

“…As it is widely known, silyl ethers are resistant to oxidation, have a good stability for most non-acidic reagents and are easily deprotected to provide the free alcohols [3]. Generally, the formation of silyl ethers carried out by treatment of parent alcohols with silyl halides or silyl triflates in the presence of stoichiometric amounts of a base [4][5][6], Li 2 S [7], and occasionally with a nonionic super base catalyst [8][9][10][11]. However, these base-catalyzed silylation methods have serious disadvantages, since careful extraction and filtration are required to remove ammonium salts derived from the reaction of by-produced acids and co-bases during the silylation reaction.…”

Diversity‐Oriented Synthesis of Functionalized 1‐Aminopyrroles by Regioselective Zinc Chloride‐Catalyzed, One‐Pot ‘Conjugate Addition/Cyclization’ Reactions of 1,3‐Bis(silyl enol ethers) with 1,2‐Diaza‐1,3‐butadienes

“…The 1-aminopyrroles prepared represent useful synthetic building blocks. For example, it has been reported previously that 1-aminopyrroles, including derivatives containing a urea moiety (similar to products 3a-as), can be transformed into the corresponding pyrroles by reaction with Cr 2 A C H T U N G T R E N N U N G (OAc) 4 , [22] KO-t-Bu/ DMF, [23] or H 2 /Raney Ni, [24] or by diazotation. [25] Scheme 2.…”