1,3-Dipolar cycloaddition of 6-(Z)-(benzoylmethylidene)penicillanate 5 with nitrile oxides 4.

Entry	4	R	Methodology	Reaction time (h)	Isolated yields (ratio)a		Overall yield
1	4b	p-FC6H4	Batch	6	6b, 72%	7b, trace amounts	72%
2	4b	p-FC6H4	MW	1	6b, 39%	7b/8b, 32% (84 : 16)	71%
3	4c	p-ClC6H4	Batch	8	6c, 49%	7c/8c, 38% (71 : 29)	87%
4	4c	p-ClC6H4	MW	1	6c, 41%	7c/8c, 29% (90 : 10)	70%
5	4d	p-BrC6H4	Batch	2	6d, 49%	7d/8d, 43% (65 : 35)	92%
6	4d	p-BrC6H4	MW	1	6d, 44%	7d/8d, 33% (58 : 42)	77%
7	4e	p-NO2C6H4	Batch	2	6e, 54%	7e/8e, 35% (34 : 66)	98%
8	4e	p-NO2C6H4	MW	1	6e, 47%	7e/8e, 32% (50 : 50)	79%
9	4f	p-MeC6H4	Batch	5	6f, 50%	7f/8f, 38% (68 : 32)	88%
10	4f	p-MeC6H4	MW	1	6f, 31%	7f/8f, 20% (85 : 15)	51%
11	4g	p-MeOC6H4	Batch	0.5	6g/8g, 52% (69 : 31)		52%
12	4g	p-MeOC6H4	MW	0.25	6g/8g, 36% (69 : 31)	7g, 21%	57%
13	4h	Cy	Batch	6	6h, 79%	7h/8h, 15% (17 : 83)	94%
14	4h	Cy	MW	1	6h, 60%	7h/8h, 10% (10 : 90)	70%

^aRatio determined by ¹H NMR.