Racemic 3-methylcyclohexene reacts with singlet dichlorocarbene to give 7,7-dichloro-2-methylbicyclo[4.1.0]heptane. The cyclopropane ring can only be cis-fused to the six-membered ring. How many stereoisomers of the product are formed in total, if enantiomers are counted separately?

The product has three stereocentres: C-1, C-6 (bridgeheads) and C-2 (bearing the methyl group). C-7 carries two identical Cl atoms and is not a stereocentre. The ring fusion must be cis, so C-1 and C-6 together give only 2 relative arrangements (one pair of enantiomeric configurations). Combined with 2 configurations at C-2 this gives $2\times 2=4$ stereoisomers: two diastereomers (methyl syn or anti to the cyclopropane ring), each as a pair of enantiomers.