Unanticipated Bicyclic Etherification in Luche Reduction: Asymmetric Total Syntheses of Diospongins A and B and Tetraketide.

In the synthesis of diospongin B based on rearrangement of δ-hydroxyalkynone to 2,3-dihydro-4H-pyran-4-one, we discovered an unanticipated beguiling reaction giving a thermodynamically less stable 4-hydroxy-2,6-trans-disubstituted-THP moiety via bicyclic etherification under Luche reduction conditions and simple acid hydrolysis. The practical applicability of this method is exemplified by the asymmetric total syntheses of diospongins A and B, several analogues, and tetraketide.

Protecting-group-directed stereodivergent Tsuji-Trost cyclization: total synthesis of oxylipids and (+)-petromyroxol.

A stereodivergent protecting-group-directed Tsuji-Trost cyclization for efficient synthesis of both 2,5-cis- and 2,5-trans-disubstituted-THF scaffolds has been realized. The presence of a ß-O-silyl group in allyl acetate results in cis-2,5-disubstituted-3-oxygenated THF in a good up to 9 : 1 dr. Alternatively, when the free OH at the ß-position is available for acetate co-ordination, it gives a trans-2,5-disubstituted-3-hydroxy THF scaffold almost as a single diastereomer (up to 1 : 0 dr). The THF scaffolds synthesized were carried forward in the total synthesis of oxylipids and (+)-petromyroxol.

Regioselective Disulfide-Catalyzed Photocatalytic Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes.

This work discloses a simple, efficient, and environmentally benevolent disulfide-catalyzed photocatalytic regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes. This methodology illustrates mild reaction conditions, ambient temperature, excellent regioselectivity, and compatibility with wide range of functional groups (38 examples). The method gains significance, as few reports with limited substrate scope are available for such excellent photocatalytic oxidative cleavage of conjugated dienes.

Emergence of 2,3,5-trisubstituted tetrahydrofuran natural products and their synthesis.

The emergence of various 2,3,5-trisubstituted tetrahydrofuran natural products in the recent literature and their synthesis is the focus of this review. These molecules exhibit varied bioactivities and have garnered the interest of several synthetic chemists owing to their efficient synthesis. A few of them have been synthesized and their absolute stereo structure has been confirmed for the first time. These will be appealing candidates in future synthetic investigations along with the untouched molecules. Thus, this compilation will reveal these molecules for expansion of their diversity within the realm of both synthesis and bioactivity studies.

Advances in Total Synthesis of Some 2,3,5-Trisubstituted Tetrahydrofuran Natural Products.

2,3,5-Trisubstituted tetrahydrofuran moiety is ubiquitous in natural products. These have served as appealing candidates for total synthesis due to their varied bio- and pharmaceutical activities. This tutorial review delineates the ingenious efforts by many researchers in the total synthesis of selected natural products based on a common 2,3,5-trisubstituted tetrahydrofuran core structure. Many of the syntheses display nuanced interplay between new methods and the ingenuity of planned strategies achieved through catalysis or cascade chemistry. In some cases, the chiron approach has come quite handy, wherein the structural features and the stereochemistry in select molecules could map well with naturally available starting materials. This compilation also aims to enhance the diversity space based on these natural products and further interest in sustainable total synthesis.