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. Author manuscript; available in PMC: 2020 May 6.
Published in final edited form as: Inorg Chem. 2019 Jun 12;58(16):10508–10515. doi: 10.1021/acs.inorgchem.9b01082

Table 2.

Alkyne Partner Substrate Scopea

graphic file with name nihms-1582301-t0010.jpg
R1, R2 % yield 4:5:6b % yield 7c % yield trimerd A valuee
1a Et, Et 5 86 8 3.5
1b nPr, nPr 4 88 9 3.6
1c TMS, H 0 >95 0 2.5
1d Ph, H 0 >95 0 3.0
1e iPr, Me 0 >95 0 3.9
1f Ph, Me 0 >95 0 4.7
1g Ph, nBu 0:4:10 19 16 4.8
1h Ph, Ph 71 0 24 6.0
1i p-CF3Ph,p-CF3Ph 64 0 19 6.0
1j p-OMe-Ph,p-OMe-Ph 78 0 15 6.0
1k p-tBuPh,p-tBuPh 76 0 22 6.0
1l Ph, TMS 8:14:26 0 0 5.5
1m nBu, TMS 0:34:31 0 0 4.3
1n Me, tBu 0 0 0 6.6
a

Reaction conditions: metallocene (0.05 mmol), alkyne (0.05 mmol), catalyst (0.0005 mmol of Ti), Zn0 (0.0005 mmol), 0.5 mL of C6H5Br, 115 °C, 3 h. Cp* = pentamethylcyclopentadiene.

b

Determined by quantitative GC-FID with respect to an internal standard (1,3,5-trimethoxybenzene).

c

Determined by 1H NMR with respect to an internal standard (1,3,5-trimethoxybenzene).

d

% yield of all alkyne cyclotrimer regioisomers; determined by 1H NMR with respect to an internal standard (1,3,5-trimethoxybenzene).

e

Sum of both alkyne substituent A values.