Malonylation/Decarbalkoxylation of Furan Derivatives as Key Steps for the Preparation of Nonactic Acid Derivatives. Part II [1]

Abstract

Summary. A malonylation=decarbalkoxylation sequence from 2-substituted furans was investigated in view of developing a scalable synthesis of hydrophobic nonactic acid analogues.

Bis(oxazolinylmethyl) Derivatives of C4H4E Heterocycles (E = NH, O, S) as C2‐Chiral Meridionally Coordinating Ligands for Nickel and Chromium

“…The synthesis of pyrrole derivative 2a by Paal–Knorr‐type cyclization was reported previously by us8 and is based on an earlier protocol by Brooker et al9a Compounds 2b and 2c are reported in the literature,9d,9e albeit by different synthetic routes and by using different precursor materials, which gave both in lower yield. In the case at hand, the acid‐catalyzed cyclization of 1 in refluxing acetic anhydride in the presence of H 2 SO 4 and subsequent workup gave 2b in 75 % yield, whereas treatment of 1 with Lawessons reagent and subsequent thermal cyclization in refluxing toluene provided a convenient route to 2c (91 % yield).…”

Macrocyclisation of 2-(5-(2-hydroxyethyl)furan-2-yl)acetic acid model compounds of nonactic acid

“…Under these modified conditions, the overall yield of macrocycles 12a-d decreased drastically. The use of the potassium cation has been reported to increase the yield of calix [9][10][11] furan formation [16], while chelation can be used for the assembly of furan rings into a macrocycle. In our case, the rigid furan rings reduce the flexibility needed for the assembly into macrocycles.…”

“…As part of our ongoing studies on macrocycle 1, we have developed a method for synthesising 2,5-disubstituted furans and tetrahydrofurans as nonactic acid precursors and analogues [9][10][11]. The key steps used to introduce the alkyl chains to the furan ring are radical couplings.…”