Atom-Economical Dimerization Strategy by the Rhodium-Catalyzed Addition of Carboxylic Acids to Allenes: Protecting-Group-Free Synthesis of Clavosolide A and Late-Stage Modification

Simmons-Smith Cyclopropanation: A Multifaceted Synthetic Protocol toward the Synthesis of Natural Products and Drugs: A Review

Simmons-Smith cyclopropanation is a widely used reaction in organic synthesis for stereospecific conversion of alkenes into cyclopropane. The utility of this reaction can be realized by the fact that the cyclopropane motif is a privileged synthetic intermediate and a core structural unit of many biologically active natural compounds such as terpenoids, alkaloids, nucleosides, amino acids, fatty acids, polyketides and drugs. The modified form of Simmons-Smith cyclopropanation involves the employment of Et2Zn and CH2I2 (Furukawa reagent) toward the total synthesis of a variety of structurally complex natural products that possess broad range of biological activities including anticancer, antimicrobial and antiviral activities. This review aims to provide an intriguing glimpse of the Furukawa-modified Simmons-Smith cyclopropanation, within the year range of 2005 to 2022.

Total Synthesis of Clavosolide A via Asymmetric Alcohol-Mediated Carbonyl Allylation: Beyond Protecting Groups or Chiral Auxiliaries in Polyketide Construction

The 20-membered marine macrodiolide clavosolide A is prepared in 7 steps (LLS) in the absence of protecting groups or chiral auxiliaries via enantioselective alcohol-mediated carbonyl addition. In 9 prior total syntheses, 11-34 steps (LLS) were required.

Glycosylation of an allenic erythronolide

A concise route to a glycosylated allenic erythronolide was achieved. Key findings include the preparation of a desosamine sulfoxide donor and the use of the donor to glycosylate bulky acceptors. Additionally, the new reagent was used to prepare allene-containing macrocycles and to realize a four-step synthesis of macrolide 6 from bis[allene] 5. The longest linear sequence required to prepare 6 from commercial reagents was 15 steps.

Rhodium-Catalyzed Diastereoselective Cyclization of Allenyl-Sulfonylcarbamates: A Stereodivergent Approach to 1,3-Aminoalcohol Derivatives

A diastereoselective and stereodivergent rhodium-catalyzed intramolecular coupling of sulfonylcarbamates with terminal allenes is described and it provides selective access to 1,3-aminoalcohol derivatives, scaffolds found in bioactive compounds. The reaction is compatible with a large range of different functional groups, thus furnishing products with high diastereoselectivities and yields. Moreover, multigram scale reactions, as well as the application of suitable product transformations were demonstrated.

Tandem Allylboration-Prins Reaction for the Rapid Construction of Substituted Tetrahydropyrans: Application to the Total Synthesis of (-)-Clavosolide A

Tetrahydropyrans are common motifs in natural products and have now been constructed with high stereocontrol through a three‐component allylboration‐Prins reaction sequence. This methodology has been applied to a concise (13 steps) and efficient (14 % overall yield) synthesis of the macrolide (−)‐clavosolide A. The synthesis also features an early stage glycosidation reaction to introduce the xylose moiety and a lithiation‐borylation reaction to attach the cyclopropyl‐containing side chain.