Ethyl N-dienyl pyroglutamates: Novel asymmetric dienes

A Novel Strategy Towards Aminophosphonic Derivatives Based on the Diels-Alder Cycloaddition: Experimental and Theoretical Approaches

“…Ethyl (2 1 a ) [67] and isopropyl N -d i e n y l -( S )pyroglutamates (21b) were prepared according to known procedures; their enantiomeric purity was assayed by chiral GC (>99.5%) Reaction of 2 1 a with trimethyl phosphonoacrylate (1) in refluxing acetonitrile for 3 days furnished a mixture of four diastereoisomers (Scheme 19; Table 3) analysed by NMR, HPLC and GC. Complete chromatographic separation of the cycloadducts 22a-25a could not be obtained, preventing an accurate determination of the diastereoselectivity [47].…”

In Situ Generation of ChiralN-Dienyl Lactams in a Multicomponent Reaction: An Efficient and Highly Selective Way to Asymmetric Amidocyclohexenes

“…[23] The corresponding diene was obtained in 39 % yield and reacted with maleic anhydride in a second step to give one diastereomeric product in 73 % yield (Scheme 3). [23] The corresponding diene was obtained in 39 % yield and reacted with maleic anhydride in a second step to give one diastereomeric product in 73 % yield (Scheme 3).…”

“…The first synthesis of an asymmetric N ‐dienyl lactam was developed by Smith and co‐workers employing ( S )‐ethyl pyroglutamate and crotonaldehyde 23. The corresponding diene was obtained in 39 % yield and reacted with maleic anhydride in a second step to give one diastereomeric product in 73 % yield (Scheme ).…”

Three-Component Reactions with (S)-Methyl Pyroglutamate: An Efficient Way to Diversely Substituted Asymmetric Amidocyclohexenes

“…[14] To discover the scope and limitations of diastereoselective AAD reactions, we were interested in whether different substitution patterns on aldehydes and dienophiles affected the stereochemical outcome. [16] In 1991, Streith and coworkers treated N-dienyl pyroglutamate 1 with acylnitroso dienophiles in Diels-Alder reactions (Scheme 4). Moreover, pyroglutamates have in the past proved to be versatile and convenient building blocks for asymmetric synthesis.…”

“…[15] The first application of pyroglutamates as an auxiliary in a sequential condensation-Diels-Alder sequence was reported by Smith and coworkers (Scheme 3). [16] In 1991, Streith and coworkers treated N-dienyl pyroglutamate 1 with acylnitroso dienophiles in Diels-Alder reactions (Scheme 4). [17] Depending on the substitution pattern at the dienophiles, the de achieved ranged from 12 to 84 %.…”