An iron-catalyzed methylene forming strategy is disclosed through sequential C–H and C–O bond functionalization of methanol with cosolvent water. This protocol provides an easy and novel access to methylene-tethered imidazo[1,2-a]pyridine and 2-aminopyridine analogues in a sustainable manner and represents a complementary approach to traditional methylene forming strategies.
A new approach for highly selective monoalkylation of active methylene and related derivatives using various types of alkylsilyl peroxides in the presence of copper catalysts under mild conditions has been developed to a synthetically useful level. This approach has a wide substrate scope in terms of both active methylene compounds and alkylsilyl peroxides. In addition, nitroalkanes can also be employed for a copper-catalyzed selective monoalkylation with alkylsilyl peroxides. The participation of radical species was proposed in the present monoalkylation reactions by the mechanistic study.
A simple and efficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.
The Michael addition and alkylation reaction of active methylene compounds (AMCs) with two active hydrogens had been investigated extensively in organic chemistry, while the polymerization of AMCs had few studies. Herein, we reported active methylene-based polyaddition and polyalkylation catalyzed via an organic superbase under ambient conditions. A model polymerization was first conducted between ethylene glycol diacrylate (EGDA) and methyl cyanoacetate (MCA). The molecular weight (Mw) of the model polymer was up to 50 500 g mol−1 with a high yield (99%). Eight AMCs were selected and a high-throughput parallel synthesizing instrument (HTPSI) was used to synthesize semi-library polymers of AMCs and EGDA via a Michael type polyaddition. The obtained AMC-based polymers had low cell cytotoxicity. Elastomers with cyanogen groups could be prepared using trimethylolpropane triacrylate (TMPTA) as a crosslinker. Furthermore, three dihalogen compounds were explored to polymerize with MCA and malononitrile via alkylation reactions. The pendent cyanogen or ester groups of the polymers could be reduced by lithium aluminum hydride. Novel polymer families were constructed based on the polyaddition and polyalkylation of AMCs.
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