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29th August 2012 @ 02:29
Mnr: 41-50
Attempts To Cyclise MNR42 without AcCl.
MNR47-1 - Yb(OTf)3 and TEA
MNR47-2 - Yb(Cl)3 and TEA
MNR47-3 - Yb(OTf)3 and lutidine
MNR47-4 - Yb(Cl)3 and lutidine

MNR47-1%20scheme.png
MNR47-1-4.PNG

Hazard Assessment
HIRAC MNR41_47_48.pdf


Procedure
To a solution of MNR42-1 (1eq) in HPLC grade acetonitrile (0.03 M) under argon at ambient temperature, was added was added base (1.4 eqs) and catalyst (0.4 eqs). The reaction was then stirred at room temperature (19 °C) for 22 hours.

Work Up

The mixture was washed saturated sodium bicarbonate solution (10 mL) and the aqueous layer was extracted with ethyl acetate (3 × 15 mL). The organic fractions were combined, dried over MgSO4, filtered and concentrated under reduced pressure to yield a yellow oil.

TLC of the crude mixtures showed MNR47-1 and MNR47-2 did not react. MNR47-3 and MNR47-4 showed signs of something but co-spotting with KAB24-2 showed it was something else. It looks like KAB24-2 has decomposed but there is still a major spot in the TLC sample.

SANY0238.JPG


TLCs in 50% EtoAc/Hex.

sample 4 = MNR47-1
sample 5 = MNR47-2
sample 6 = MNR47-3
sample 7 = MNR47-4

Column

MNR47-3 was ran through a column using 40% EtOAc/Hex.

upon drying the fractions that contained the lower running spot, next to nothing was recovered. NMR confirmed this with no distinguishable peaks found. This confirms that the spot was due to lutidine from the reaction which has been lost on the hi-vac.

Conclusions

MNR42-1 can not be cyclised using Yb(OTf)3 or Yb(Cl)3 in the absence of AcCl.
Attached Files
MNR47-1 scheme.png
MNR47-1-4.PNG
SANY0238.JPG