Highly Stereo- and Regioselective Synthesis of (Z)-Trisubstituted Alkenes via 1-Bromo-1-alkyne Hydroboration−Migratory Insertion−Zn-Promoted Iodinolysis and Pd-Catalyzed Organozinc Cross-Coupling

Abstract

Hydroboration of 1-bromo-1-alkynes with dibromoborane followed by addition of 3 or 4 equiv of Me 2 Zn provides an efficient and selective route to (Z)-2-alkenyldimethylboranes (3) or (Z)-2-alkenylmethylzincs (4), respectively, which have been successfully applied to one-pot Suzuki (B-I) or Negishi (Zn-I) coupling in some less demanding cases. However, in more demanding crosscoupling reactions, only the use of either (Z)-2-alkenyliodides (5) or the alkenylzincs prepared from lithiation and then zincation of 5 proves to be highly satisfactory (Zn-II or Zn-III protocol). On the contrary, the corresponding organoboron coupling under B-II or B-III protocol appears to be less satisfactory. Preliminary studies indicate that certain substituents proximal to trisubstituted alkenes seriously affect the course of the desired alkenylboron cross-coupling.

Immobilization and Continuous Recycling of Photoredox Catalysts in Ionic Liquids for Applications in Batch Reactions and Flow Systems: Catalytic Alkene Isomerization by Using Visible Light

“…Whereas the ( E )‐alkene is readily accessible, the synthesis of the ( Z )‐isomer still poses a major challenge. Current procedures for the synthesis are Wittig reactions,7 the Still–Gennari modification of the Horner–Wadsworth–Emmons reaction,8 Pd‐9 and Ni‐catalyzed10 cross‐couplings of ( Z ) ‐ alkenyl halides, stereoselective reductions of alkynes by Lindlar catalysis11 or hydrometalations, ( Z )‐selective metathesis,11 the Shapiro reaction12 and Peterson olefinations 13. The highlighted reactions allow no subsequent modifications of the double bond geometry.…”

Die magische Kraft der Übergangsmetalle: Vergangenheit, Gegenwart und Zukunft (Nobel‐Aufsatz)

“…Alle Originalarbeiten und einschlägigen Übersichten zur ZACA-Reaktion aus der Arbeitsgruppe des Autors sind in den Literaturzitaten genannt. [63,69,75,84,87, 1) Die ZACA-Reaktion ist eine neue und seltene katalytische asymmetrische C-C-Verknüpfungsreaktion terminaler Alkene und erfordert keine anderen funktionellen Gruppen, auch wenn verschiedene funktionelle Gruppen vorliegen können.…”

“…Bürzeldrüsenwachs der Graugans, Anser anser (2006) [104] Totalsynthese 14 Doliculid, Fragment C1-C9 (2006) [104] Fragment C1-C9 [106] Seitenkette C5-C11 17 (À)-Spongidepsin (2007) [107] Totalsynthese 18 (+)-Discodermolid (2007) [75] Fragment C11-C17…”

“…19 (À)-Callystatin A (2007) [75] Fragment C1-C11 20 Archazolide A und B (2007) [75] A: R = Me, B: R = H Fragment C7-C15…”

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

“…The important biological properties in combination with their limited natural supply as well as their intriguing molecular architectures and initially unknown stereochemistry, have rendered the archazolids as highly attractive synthetic targets and so far, three total syntheses have been reported by the groups of Menche and Trauner [41–43]. Furthermore several fragment syntheses as well as methodological studies to access key structural elements have been published in the last years [44–54]. Recently, the focus has been increasingly shifted towards analog development and SAR studies [49,55–58] and the group of O’Neil has been targeting dihydroarchazolid B ( 3 ) as a potentially equipotent structurally simplified derivative [45–46 48].…”