Reaction of alkenylboronic acids with iodine under the influence of base.  Simple procedure for the stereospecific conversion of terminal alkynes into trans-1-alkenyl iodides via hydroboration

Brown, Herbert C.; Hamaoka, Tsutomu; Ravindran, N.

doi:10.1021/ja00798a071

Cited by 163 publications

(48 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The substituted vinyl boronates, e.g. 237, 240, 243 thus obtained can readily and stereoselectively be converted to vinyl bromides and iodides, using the halogenation procedures reported by Brown et al (Scheme 70) [78]. In agreement with Brown's observations, vinyl bromides, e.g.…”

Section: CMsupporting

confidence: 80%

Metathesis of heteroatom-substituted olefins and alkynes: Current scope and limitations

Weghe

Bisseret

Blanchard

et al. 2006

Journal of Organometallic Chemistry

View full text Add to dashboard Cite

Section: CMsupporting

confidence: 80%

Metathesis of heteroatom-substituted olefins and alkynes: Current scope and limitations

Weghe

Bisseret

Blanchard

et al. 2006

Journal of Organometallic Chemistry

View full text Add to dashboard Cite

“…Functionalization of the internal acetylene of 7a was realized through standard Pd-catalyzed hydrostannylation conditions to initially provide vinyl stannane 57 in only 25% yield along with recovered starting material (Scheme 17). Screening of other hydrometallation protocols, including hydrozirconation, 45 hydroboration, 46 and hydroalumination, 47 either resulted in recovery of starting material or reduction of the N -Ts lactam moiety. The steric congestion around this internal alkyne due to the cyclohexyl ring and adjacent quaternary carbon posed a considerable challenge to this otherwise standard transformation.…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of the Spirocyclic Imine Marine Toxin (−)-Gymnodimine and an Unnatural C4-Epimer

Kong¹,

Moussa²,

Lee³

et al. 2011

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The first total synthesis of the marine toxin (−)-gymnodimine (1) has been accomplished in a convergent manner. A highly diastereo- and enantioselective exo-Diels–Alder reaction catalyzed by a bis-oxazoline Cu(II) catalyst enabled rapid assembly of the spirocyclic core of gymnodimine. The preparation of the tetrahydrofuran fragment utilized a chiral auxiliary based anti-aldol reaction. Two major fragments, spirolactam 56 and tetrahydrofuran 55, were then coupled through an efficient Nozaki–Hiyama–Kishi reaction. An unconventional, ambient temperature t-BuLi-initiated intramolecular Barbier reaction of alkyl iodide 64 was employed to form the macrocycle. A late stage vinylogous Mukaiyama aldol addition of a silyloxyfuran to a complex cyclohexanone 83 appended the butenolide and a few additional steps provided (−)-gymnodimine (1). A diastereomer of the natural product was also synthesized, C4-epi-gymnodimine (90), derived from the vinylogous Mukaiyama aldol addition.

show abstract

“…8 Thus, 1,3-butadiene and 1,3-cyclohexadiene reacted faster in the presence of CoCh(dppp) than NiCI 2 (dppp). Thus, 1,3-butadiene gave 1,2-and 1,4-addition products (86 : 14). A dramatic difference of activity was observed for 1,3-cyclopentadiene reacting readily in the presence of NiClo(dppp) whereas CoCI 2 (dppp) was not active.…”

Section: Monohydroboration Of Conjugated Dienes Alkynes Andmentioning

confidence: 99%

Monohydroboration of Conjugated Dienes, Alkynes and Functionalized Alkynes With Catecholborane Catalyzed by Nickel(ii) Chloride and Cobalt(ii) Chloride Complexes With Phosphines

Zaidlewicz¹,

Melier²

2000

Main Group Metal Chemistry

View full text Add to dashboard Cite

The catalytic activity of nickel(U) chloride and cobalt(ll) chloride complexes with selected phosphines in the hydroboration of conjugated dienes, alkynes and derivatives with catecholborane has been examined. In the presence of CoCI 2 (dppp) 1,2-and 1,4-addition products to dienes are obtained, whereas NiCl 2 (dppe) and NiCljidppp) favor 1,2-addition products. Higher regioselectivity of addition to terminal alkynes and to trimethylsilylacetylene in the reactions catalyzed by NiCI 2 (dppe), as compared to the uncatalyzed reactions, has been achieved. Homopropargylic derivatives can be cleanly monohydroborated under very mild conditions in the presence of this catalyst. RESULTS AND DISCUSSIONNickelocene, cyclopentadienylnickel(II) chloride and nickel(II) chloride complexes with triphenylphosphine, nickel(U) chloride and cobalt(ll) chloride complexes with l,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), and l,4-bis(diphenylphosphino)butane (dppb), were chosen as catalysts. Since catecholborane undergoes disproportionation in the presence of certain metal salts, the stability of its 1 Μ solutions in tetrahydrofuran containing 1 % molar of the above mentioned compounds was monitored by "B NMR analysis. For all the compounds examined, the catecholborane signal at 526.0 remained the main signal in the spectrum after 24 h at room temperature. In the presence of nickelocene and cyclopentadienylnickel(II) chloride complex with triphenylphosphine a small peak at δ 0.5 corresponding to borane-tetrahydrofuran and a signal at δ 20.0 were observed. In the presence of the other compounds the spectra did not show a borane signal. A signal at Ö20.0, corresponding to a borate ester, integrating for 3-12 % of the total area of the signals, and not increasing in intensity after 48 h, was present. The lack of the signal corresponding to borane-tetrahydrofuran, a possible disproportionation product, indicates the stability of catecholborane in the presence of these compounds. Conjugated dienes.The catalytic activity of the chosen compounds in the reactions of catecholborane with isoprene and 2,3-dimethyl-l,3-butadiene was examined in comparison to 1-alkenes. The reactions were carried out at 1 : 1 molar ratio at room temperature using the solutions described above. As shown in Table 1, hydroboration of 1-alkenes in the presence of the nickel compounds and CoCI 2 (dppb) gave either low yields or no product. In contrast, isoprene reacted with catecholborane in the presence of NiCI 2 (dppp) and CoCl 2 (dppp) to give 79 % of the product in 6 h and 24 h, respectively. It is interesting to note that the order of activity CoCI 2 (dppp) > CoCl 2 (dppe)» CoCl 2 (dppb) does not parallel the corresponding nickel(II) chloride complexes NiCI 2 (dppe) > NiCI 2 (dppp) > NiCl 2 (dppb). Nickelocene and nickel(II) chloride complex with triphenylphosphine showed a low activity, similarly to the reactions with 1-alkenes. Consequently, NiCI 2 (dppp) and CoCI 2 (dppp) were used as catalysts for the reactions of representat...

show abstract

Reaction of alkenylboronic acids with iodine under the influence of base. Simple procedure for the stereospecific conversion of terminal alkynes into trans-1-alkenyl iodides via hydroboration

Cited by 163 publications

References 0 publications

Metathesis of heteroatom-substituted olefins and alkynes: Current scope and limitations

Metathesis of heteroatom-substituted olefins and alkynes: Current scope and limitations

Total Synthesis of the Spirocyclic Imine Marine Toxin (−)-Gymnodimine and an Unnatural C4-Epimer

Monohydroboration of Conjugated Dienes, Alkynes and Functionalized Alkynes With Catecholborane Catalyzed by Nickel(ii) Chloride and Cobalt(ii) Chloride Complexes With Phosphines

Contact Info

Product

Resources

About