Synthesis of Alkaloid Analogues from α‐Amino Acids by One‐Pot Radical Decarboxylation/Alkylation

Abstract

A mild, one‐pot methodology to obtain α‐substituted nitrogen heterocycles from commercial amino acids is reported. This versatile procedure has been applied to the synthesis of different alkaloid analogues in good to excellent yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis of 5-Substituted 2-Pyrrolidinones by Coupling of Organozinc Reagents with Cyclic N-Acyliminium Ions

“…To this end, pyrrolidinone 4f was reacted with allyl bromide to give N-allyl pyrrolidinone 4h in 55% yield, and with homoallyl bromide to give N-homoallyl pyrrolidinone 4i in 63% yield under conditions reported by Boto. 24 Finally, 5-allyl pyrrolidinones 4h and 4i were reacted with Grubbs' catalyst using the RCM conditions reported by Meyers 25 to give the desired azabicyclic systems 6 and 7 in good yields of 81% and 70%, respectively.…”

A Simple Enantioselective Route to Functionalized Indolizidines: Synthesis of (+)‐Ipalbidine and (+)‐Antofine

“…Aryl‐substituted indolizidines are also of interest; either as bioactive natural products4 or as peptidomimetics 5. Accordingly, the synthesis of arylindolizidines continues to be intensely investigated and general synthetic strategies toward aryl‐fused6a–6c or aryl‐substituted indolizidines6d–6h as well as other, functionalized indolizidines have been reported 7. Herein, we describe a concise and stereoselective synthesis of the arylindolizidine alkaloid (+)‐ipalbidine ( 1 , Figure 1),8 a non‐addictive analgesic9 and oxygen free‐radical scavenger,10 and the phenanthroindolizidine alkaloid (+)‐antofine ( 2 ),11 the enantiomer of which has potent anticancer12 and antiviral acitvity 13.…”

One-Pot Stereoselective Synthesis of 1,2-Amino Alcohol Derivatives

“…A variation of the scission–alkylation process allowed us to obtain chiral bicyclic and polycyclic systems. In this variation, the decarboxylation was coupled to an aza-Diels–Alder cyclization . The optimization of the reaction conditions is shown in Table , using 2,3-dimethyl-1,3-butadiene as the diene, to give the bicyclic product 15 .…”