A Metal-Free Tandem C–C/C–O Bond Formation Approach to Diversely Functionalized Tetrasubstituted Furans

Abstract

A novel and efficient method for the synthesis of diversely functionalized furans is developed via DBU-mediated tandem Michael addition/5-exo-dig-cycloisomerization of enynes and keto-methylenes. This [3 + 2]-annulation is operationally simple under metal-free reaction conditions with 100% atom economy and broad substrate scope.

Stereoselective Synthesis of (3S, 4R)-5-Phenylpentane-1, 3, 4-Triol

“…[α]D20 +63.9 (c 0.12, MeOH); 1 H NMR (300 MHz, CDCl 3 ): δ 7.27-7.32 (m, 2H), 7.19-7.24 (m, 3H), 3.77-3.87 (m, 4H), 2.83 (dd, J = 14.0, 3.7 Hz, 1H), 2.69 (dd, J = 13.9, 9.0 Hz, 1H), 1.75-1.81 (m, 2H); 13…”

“…In addition to this their synthetic analogues are important as lead structures or drug candidates for the discovery of novel drugs [6][7][8][9]. These compounds have explicitly exhibited a broad spectrum of biological activities including antibacterial, antitumoral, antimicrobial, antifeedant, herbicidal, plant growth inhibition and the inhibition of cholesterol biosynthesis properties [10][11][12][13][14]. Recently Hirokazu Kawagishi et al isolated the triol compound named (3S,4R)-5-Phenylpentane-1,3,4-triol (1, Scheme 1) from the EtOH extract of edible mushroom Mycoleptodonoides aitchisonii [15].…”

Synthesis of ynones at room temperature catalyzed by copper chloride cryptand complex under solvent free conditions

“…Ynones are the constructive building blocks in organic chemistry that are used as synthetic intermediates for the preparation of many biologically-active compounds, heterocyclic derivatives [1] etc. Ynones are also precursors for the synthesis of various valuable organic functional groups like isoxazoles [2a], pyrimidines [2b], quinolones [3], furans [4], pyrazoles [5], flavones [6], oximes [7], polyfunctionalized pyrroles [8], chiral propargylic alcohols [9] and many more. There are various reaction protocols that have been reported for the synthesis of ynones which include oxidation of propargylic alcohols [10], coupling reactions of terminal alkynes with organic halides in the presence of carbon-monoxide gas [11], oxidation of alkynes [12], reaction of terminal alkynes with nitriles [13], and the most important method is the reaction between terminal alkynes and carboxylic acid derivatives in the presence of various strong bases [14] and elements such as silver [15], zinc [16], tin [17], silicon [18], lithium [19], copper [20], magnesium [21], cadmium [22], aluminum [23], thallium [24], gallium [25], stibium [26], indium [27], etc.…”

Synthetic Studies toward (±)-Furanocembranoid 1: Construction of the Acyclic Carbon Framework

“…3−5 Recently, we have also successfully explored the cycloisomerization of enynols for the synthesis of substituted furans. 6 On this basis, we considered that cyclodehydration of enyne-diol 7,8 could be a key step in the late-stage construction of the 2,4-disubstituted furan core of furanocembranoid 1. Scheme 1 outlines our retrosynthetic analysis of 1a .…”