Table 1. rDA studies of azabicycle-cysteine adducts.

Entry	Vinyl sulfone a	Azabicycle-Cys adduct	R	P	Solvent	Half-life
1	1	2	H	Boc	CDCl3	16.4 h
2	5	6 b	Me	Boc	CDCl3	<5 min
3	7	8	H	Ac	CDCl3	37 h c
4	7	8	H	Ac	DMSO-d6	59 h

^aSee ESI for details on the synthesis of vinyl sulfones 5 and 7.

^bAzabicycle-cysteine adduct 6 was not observed because it decomposes directly to give 9 and N-Boc-2,5-dimethylpyrrole.

^c t _1/2 = 40 h; CDCl₃ is pre-neutralized with K₂CO₃.