CC Linkage of Carboxylic Acids with Allyl Alcohols Using 2‐Phenylglycine as Vehicle

Abstract

A new method for the chain elongation of carboxylic acids leads to ketones under very mild conditions. Organometallic intermediates are avoided. The 2‐phenylglycine used as “vehicle” does not appear in the final product.

Chemoenzymatic Synthesis of Unnatural Amino Acids via Modified Claisen Rearrangement of Glycine Enolates. Approach to Morphine Synthesis

“…Arene cis -diols of the type 4 have been reasonably exploited in asymmetric synthesis as indicated by vigorous synthetic activity. , As of this writing, no report exists on the application of Claisen rearrangement to either of the allylic systems in 4 , even though this was suggested in our first publication in this area . The first synthesis of amino acids by Claisen rearrangement was described in 1975 by Steglich . Since 1982, when the Ireland−Claisen rearrangement of glycine allylic esters was reported by Bartlett and co-workers, this method has found ample application in amino acid synthesis …”

“…7 The first synthesis of amino acids by Claisen rearrangement was described in 1975 by Steglich. 8 Since 1982, when the Ireland-Claisen rearrangement of glycine allylic esters was reported by Bartlett and co-workers, 9 this method has found ample application in amino acid synthesis. 10 In 1994, a variation of the Claisen rearrangement was reported by Kazmaier,11 in which the silylketene acetals were replaced by chelate-bridged metal enolates, claimed to be superior to ketene acetals both in terms of their selectivity (fixed configuration of the enolate) and reactivity (anion accelerated rearrangement).…”

5‐Alkoxyoxazole – A Versatile Building Block in (Bio)organic Synthesis

“…However, when R 1 = H, a mixture of diastereomers was formed, which is presumably the result of the facile isomerization of the synthesized oxazolones . Steglich et al subsequently reported a one‐pot successive Claisen/Cope [3,3] sigmatropic rearrangement . Similarly, when allylic amido esters were replaced by propargylic derivatives, the corresponding 4‐allenyl‐substituted oxazolinones 127 were obtained (Scheme , b).…”

Total Synthesis of a Marine Alkaloid from the Tunicate Dendrodoa grossularia

“…As a continuation of our laboratory’s focus on the development of new heterocyclic methodologies for the syntheses of pharmacologically significant scaffolds, we report the racemic total synthesis of indole alkaloid 1 , producing an oxazolone intermediate, ultimately leading to a quaternary hydantoin.…”

“…It was envisioned that the imidazolone moiety of the natural product could be accessed from the hydantoin intermediate 7 . Through an underutilized oxazole rearrangement, first described by Steglich and co-workers, , hydantoin 7 was thought to be formed from thiourea 6 . In turn, thiourea 6 could be obtained from keto allyl ester 2 after a few functional group manipulations.…”