Enantioselective synthesis of (+)-gossonorol and related systems using organozinc reagents

Harnessing the Power of the Asymmetric Grignard Synthesis of Tertiary Alcohols: Ligand Development and Improved Scope Exemplified by One-Step Gossonorol Synthesis

“…Five diverse synthetic approaches for the enantioselective synthesis of gossonorol have been reported in the literature. Among the strategies used are the chiral base-mediated functionalization of chromium complexes of protected benzyl ethers, bromolactonization, and titanium-promoted dialkyl zinc addition to ketones . These methods require up to seven synthetic steps.…”

“…Among the strategies used are the chiral base-mediated functionalization of chromium complexes of protected benzyl ethers, 18 bromolactonization, 19 and titanium-promoted dialkyl zinc addition to ketones. 21 These methods require up to seven synthetic steps. Most notably, in 2012, Aggarwal and co-workers employed the lithiation−borylation strategy to generate this target in three steps with excellent selectivity (98% ee).…”

Enantioselective Organocatalyzed Bromolactonizations: Applications in Natural Product Synthesis

“…Hence, starting from the commercially available ester methyl hex-5-ynoate, (−)-gossoronol ( 7 ) was prepared over seven steps and in 34% yield and >99% ee. All physical and spectral data were in accordance with naturally occurring and synthetic material of 7 . , In addition, these efforts also constitute a formal synthesis of yingzhaosu C ( 8 ) . (−)-Gossoronol ( 7 ) was then further elaborated into (−)-boivinianin B ( 9 ) through the use of the Shi epoxidation reaction .…”

“…To further demonstrate the synthetic potential of the described protocol, it was employed in the total synthesis of natural products. The bisabolane sesquiterpene (−)-gossonorol ( 7 ) , and the related natural products yingzhaosu C ( 8 ) , and (−)-boivinianin B ( 9 ) , were selected as suitable targets, due to their interesting biological activities against fungi, cancer, and malaria. Furthermore, the developed bromolactonization protocol offers the possibility of controlling the absolute configuration of the benzylic position in 7 – 9 , making it an interesting tool for establishing the mentioned target molecules.…”

The pinene scaffold: its occurrence, chemistry, synthetic utility, and pharmacological importance

“…Secondary alcohols are key intermediates in the synthesis of natural products such as (+)-(R)gossonorol (Fig. 12) 72,73 which was studied for its antifungal and antitumor activities.…”