May Chazaras Hashatz be recited if only five people Davened together?
In the event that Shemoneh Esrei was Davened with less than six people, it is nevertheless permitted for the Chazan to recite the repetition for the sake of the Kedusha. (Nevertheless, it is not considered that the congregation has Davened with a Minyan, and the above repetition does not have the status of a regular Chazaras Hashatz.) However, initially in such a case, instead of Davening Shemoneh Esrei in silent and then repeating Shemoneh Esrei for the sake of the Kedusha, the Chazan is to Daven his silent Shemoneh Esrei aloud until after Kedusha and then recite the remainder of Shemoneh Esrei in silent.
 Admur 69/4-5; Piskeiy Teshuvos 69/1
 Admur 69/4; Michaber 69/1; Tehila Ledavid 69/2; Ashel Avraham Butchach 69; Imrei Yosher 2/9; Afrasakta Deanya 2/16; Minchas Yitzchak 1/57 and 10/107
Other opinions: Some Poskim question if according to the Radbaz 4/241, brought in M”A 69/4, one may recite the repetition for the sake of the Kedusha in such a case. [Biur Halacha 69/1 “Omer”]
 See Admur 69/5 in parentheses
 Admur 69/5; M”A 69/4; Piskeiy Teshuvos 69/1