Synthesis of macrocyclic cyclophane-based unusual α-amino acid derivatives

Abstract

Alkylation of ethyl isocyanoacetate with 1,2-bis(4-bromomethylphenyl)ethane under phase transfer catalysis (PTC) as well as phosphazene base [2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP)] conditions gave the macrocyclic cyclophane based unusual α-amino acid derivatives.

Isocyanoacetate Derivatives: Synthesis, Reactivity, and Application

“…65 When 2 equiv of alkylating agent (n-alkyl or benzyl halide) is used, dialkylated products 122 can be obtained in yields up to 90% (Scheme 24). [66][67][68][69] However, monoalkylation of isocyanoacetate can be accomplished with tert-butyl ester 123, since here the bulky ester group prevents attack of the R-anion to a second alkyl halide molecule (Table 3). 66,67 Initially, alkylation was performed with t-BuOK or NaH as a base.…”

“…Usually, alkylation of metalated unsubstituted methyl or ethyl isocyanoacetates leads to dialkylation products (in several cases intermediate monoalkylated products can be isolated in 10−20% yields) . When 2 equiv of alkylating agent ( n -alkyl or benzyl halide) is used, dialkylated products 122 can be obtained in yields up to 90% (Scheme ). − …”

Diversity-Oriented Approaches to Unusual α-Amino Acids and Peptides: Step Economy, Atom Economy, Redox Economy, and Beyond

“…Treatment of the dibromide 197 under basic conditions [2- tert -butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP)] afforded 198 as an isomeric mixture. This mixture 198 on acid hydrolysis afforded the N -formylcyclophane derivative 199 (Scheme ) …”

Synthesis of Diverse Polycyclic Compounds via Catalytic Metathesis

“…Compound 54 was then converted into the N-formyl and N-acetyl derivatives 55a and 55b, respectively, under the appropriate conditions (Scheme 9). 20,21 The RCM reaction of compounds 55a and 55b in the presence of 11 in refluxing benzene gave the starting material. Since styrene derivatives 55 did not undergo RCM, the corresponding diallyl derivatives, such as 59, were considered better substrates.…”