Generation of Nonracemic 2‐( t ‐Butyldimethylsilyloxy)‐3‐butynyllithium from ( S )‐Ethyl Lactate:

Abstract

(S) ‐4‐(Butyldimethylsiloxy)‐2‐pentynal (S)‐ Ethyl 2‐(‐ tert‐ butyldimethoxysiloxy)propanoate Rochelle salt DIBAL‐H (S)‐ 2‐ (tert‐ Butyldimethylsiloxy)propanal 1‐Dichloro‐(3 S)‐(tert‐ butyldimethylsiloxy)‐2‐butyl p‐ toluenesulfonate

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

“…1-Haloalkynes were prepared according to literature procedures 82,91–95. Chiral aldehydes were prepared by literature methods;74,96–98 either Swern oxidation of the primary alcohol or DIBAL-H reduction of the methyl ester was performed to generate the crude chiral aldehydes just prior to reaction. These aldehydes were used without further purification due to their sensitivity.…”

Total Synthesis and Absolute Configuration of the Bisanthraquinone Antibiotic BE‐43472B

“…Starting with ( R )‐(+)‐ 7 (derived from unnatural ( R )‐(+)‐lactic acid methyl ester)6 we then synthesized (+)‐ 1 , the naturally occurring enantiomeric form of antibiotic BE‐43472B; it is this synthesis we describe herein. Wittig reaction7 of aldehyde (+)‐ 7 with phosphorane 6 gave α,β‐unsaturated ester 8 (95 % yield, E / Z >95:5), which was converted to ketone 10 (57 % yield over two steps) by addition of MeLi to the intermediate Weinreb amide 9 8.…”

Total Synthesis and Absolute Configuration of the Bisanthraquinone Antibiotic BE‐43472B

“…[2] As events transpired, this choice led to (−)- 1 , the enantiomer of BE-43472B. Starting with ( R )-(+)- 7 (derived from unnatural ( R )-(+)-lactic acid methyl ester)[6] we then synthesized (+)- 1 , the naturally occurring enantiomeric form of antibiotic BE-43472B; it is this synthesis we describe herein. Wittig reaction[7] of aldehyde (+)- 7 with phosphorane 6 gave α,β-unsaturated ester 8 (95 % yield, E/Z >95:5), which was converted to ketone 10 (57 % yield over two steps) via addition of MeLi to the intermediate Weinreb amide 9 .…”