Table 4.

The stability of compounds 8/9 during the McKenna reaction.^a,b.

compound			silylation			solvolysisc
entry	R	R1	amine (equiv)	time (h)	ester bond cleavage	BTMS	molar ratio 24:25:26 (time)
1	H	Et	–	24	0	–	0.98:0.02:0 (24 h)
2	H	Et	–	24	0	+	0.63:0.07:0.30 (18 h)d
3	H	t-Bu	–	1 24	30% 100%	– –	0:1:0 (1 h) –
4	H	t-Bu	TEA (1)	1 24	0 44%	–	– 0.5:0.5:0e
5	H	t-Bu	pyridine (1 or 2)	24	47%	–	0.5:0.5:0
7	3-Py-CH2-	t-Bu	–	24	0	–	1:0:0 (24 h)
8	3-Py-CH2-	t-Bu	–	24	0	+	0:1:0

^aReaction carried out in CD₃CN at rt with 12 equiv BTMS (distilled), unless defined otherwise; ^bfor analogs R = H, the McKenna reaction completed within 1 h; for analogs R = pyridin-3-ylmethyl, the McKenna reaction was completed within 2 h; ^cthe experiment was run on the same sample as the one used for the BTMS studies. For this, the sample was evaporated and directly subjected to solvolysis with MeOD/D₂O 20:1 (v/v) for 5–10 minutes, unless stated otherwise in parentheses; ^dsolvolysis: MeOH/H₂O 40:1, BTMS (0.5 equiv); ^ethe same result was obtained after 24 h.