Pd-catalyzed carbonylative cross-coupling
reactions of 2-iodoglycals
have been developed for the synthesis of sugar-based arylones and
ynones using formic acid as the carbonyl source. Whereas acetyl-protected
arylones lead to the formation of highly substituted furan derivatives
in the presence of Lewis acid, benzyl-protected arylones furnished
the 3-deoxy sugar derivative. In the presence of nucleophiles, an
attack took place on the C-1 or C-3 carbon regio- and stereoselectively
depending on the nature of the nucleophiles.
Carbonylation reactions under transition metal catalysis have emerged as one of the most important strategies for the construction of CO inserted molecules having both industrial and material applications. Hence the most widely used protocol for the insertion of CO is by the utilization of CO (gas) but this method limits its applicability in industrial-scale carbonylation due to toxic and explosive nature. To use more cheaper and environmentally benign methods the chemistry of CO surrogates gained considerable attention with the emergence of newer methods and CO surrogates. Aldehydes, formate esters, formamides, and metal carbonyls are the some of the CO surrogates that have been extensively utilized in recent times for the synthesis of industrial bulk chemicals as well in small scale synthesis of pharmacological building blocks. In this review, we have summarized the recent development in carbonylation reactions by utilization of formic acid as CO surrogate.
A visible light-mediated approach enabling the use of alcohols as nucleophiles in a one-step synthesis of α-alkoxy/hydroxy diarylacetaldehydes has been reported. The method allows the construction of a highly functionalized...
Glycals are unsaturated sugars having an enolic double bond present inside the ring and act as a versatile synthon for the synthesis of natural products and biologically important molecules. The lone pair of endocyclic ring oxygen which is in conjugation with the enolic double bond alters the reactivity of both unsaturated carbons of glycals and directs the selectivity of the incoming group at a particular center. Since the enolic double bond is very much prone to undergo various types of reactions such as epoxidation, addition, formylation, nitration halogenation, etc.; and such type of activated glycals or the derivatives of glycal have been extensively utilized as a precursor for the synthesis of branched sugars. 2-haloglycals have emerged as an important building block for the functionalization at C-2 position of glycals via metal-catalyzed cross-coupling reactions such as Heck, Suzuki, Sonogashira and carbonylative cross-coupling reactions. In this review, we have summarized the recent progress on the utilization of 2-haloglycals for the synthesis of 2-C-branched sugars and further transformation of branched sugars into annulated sugars, heterocycles, and glycoconjugates.[a] Dr.
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