- Oxidative Addition of Alkenyl and Alkynyl Iodides to a AuI Complex
-
The first isolated examples of intermolecular oxidative addition of alkenyl and alkynyl iodides to AuI are reported. Using a 5,5′-difluoro-2,2′-bipyridyl ligated complex, oxidative addition of geometrically defined alkenyl iodides occurs readily, reversibly and stereospecifically to give alkenyl-AuIII complexes. Conversely, reversible alkynyl iodide oxidative addition generates bimetallic complexes containing both AuIII and AuI centers. Stoichiometric studies show that both new initiation modes can form the basis for the development of C?C bond forming cross-couplings.
- Bower, John F.,Cadge, Jamie A.,Russell, Christopher A.,Sparkes, Hazel A.
-
supporting information
p. 6617 - 6621
(2020/03/13)
-
- Callipeltosides A, B and C: Total Syntheses and Structural Confirmation
-
Since their isolation almost 20 years ago, the callipeltosides have been of long standing interest to the synthetic community owing to their unique structural features and inherent biological activity. Herein we present our full research effort that has led to the synthesis of these molecules. Key aspects of our final strategy include 1) synthesis of the C1-C9 pyran core (5) using an AuCl3-catalysed cyclisation; 2) formation of C10-C22 vinyl iodide (55) by sequential bidirectional Stille reactions and 3) diastereoselective union of these advanced fragments by means of an alkenylzinc addition (d.r.=91:9 at C9). The common callipeltoside aglycon (4) was completed in a further five steps. Following this, all three sugar fragments were appended to provide the entire callipeltoside family. In addition to this, D-configured callipeltose B was synthesised and appended to the callipeltoside aglycon. The 1H NMR spectrum of this molecule was found to be significantly different to the natural isolate, further supporting our assignment of callipeltoside B (2). Easy as A, B, C: The entire callipeltoside family of natural products have been synthesised in a highly convergent manner. This account details our full research effort and presents further evidence to aid in the stereochemical assignment of the glycosidic linkages present in callipeltosides B and C (see scheme).
- Frost, James R.,Pearson, Colin M.,Snaddon, Thomas N.,Booth, Richard A.,Turner, Richard M.,Gold, Johan,Shaw, David M.,Gaunt, Matthew J.,Ley, Steven V.
-
supporting information
p. 13261 - 13277
(2015/09/15)
-
- Sterically biased 3,3-sigmatropic rearrangement of chiral allylic azides: Application to the total syntheses of alkaloids
-
(Chemical Equation Presented) We describe a tandem Mitsunobu/3,3- sigmatropic rearrangement of allylic azides on a chiral auxiliary system that favors one regioisomer thanks to its exceptional steric bias. The sequence may be completed by the oxidative cleavage of the auxiliary or by a ring-closing metathesis reaction that produces a carbo-or heterocycle directly and a recyclable form of the chiral auxiliary. Applications of the methodology to the total synthesis of (+)-coniine, (+)-lentiginosin, and (+)-pumiliotoxin C are reported.
- Lauzon, Sophie,Tremblay, Francois,Gagnon, David,Godbout, Cedrickx,Chabot, Christine,Mercier-Shanks, Catherine,Perreault, Stephane,DeSeve, Helene,Spino, Claude
-
p. 6239 - 6250
(2008/12/22)
-
- Synthetic studies on halichondrins: A practical synthesis of the C.1-C.13 segment
-
A practical, scalable synthesis of the C.1-C.13 segment of halichondrin B has been developed starting from L-mannonic-γ-lactone, using C-allylation/oxy-Michael cyclization and Ni(II)/Cr(II)-mediated vinyltrimethylsilane addition to set the C.6/C.3 and C.11 stereocenters, respectively.
- Stamos, Dean P.,Kishi, Yoshito
-
p. 8643 - 8646
(2007/10/03)
-