Highly Stereoselective Synthesis of <i>anti</i>,<i>anti</i>-Dipropionate Stereotriads: A Solution to the Long-Standing Problem of Challenging Mismatched Double Asymmetric Crotylboration Reactions
作者:Ming Chen、William R. Roush
DOI:10.1021/ja300472a
日期:2012.2.29
aldehydes with the chiral, nonracemic crotylborane reagent (S)-(E)-22 (or its enantiomer). This method not only provides direct access to anti,anti-dipropionate stereotriads 24 [a synthetic equivalent of 4] with very good (5-8:1) if not excellent (≥15:1) diastereoselectivity from β-branched chiral aldehydes with ≤50:1 intrinsic diastereofacial selectivity preferences but also provides a vinylstannane
作者:Tushar Kanti Chakraborty、Amit Kumar Chattopadhyay
DOI:10.1021/jo800181n
日期:2008.5.1
A convergent totalsynthesis of the cytotoxic natural product cruentaren B is completed in 26 steps (longest linear sequence) with an overall yield of 7.1%. For the construction of the C1−C11 benzolactone fragment of the molecule, the key steps used were O-methylation, using a Mitsunobu reaction, a Stille coupling method to construct the C7−C8 bond, and a Brown’s asymmetric crotylboration reaction
A flexible route for the stereoselective synthesis of the key skeleton of mohangic acids A−E has been developed. Notably, intermolecular Heck coupling has been introduced to couple an unactivated alkene with an iodo-diene counterpart to install the required triene system of the molecules. The developed strategy is highly modular.